How can you encode a string to Base64 in JavaScript

Question

I have a PHP script that can encode a PNG image to a Base64 string   I d like to do the same thing using JavaScript  I know how to open files  but I m not sure how to do the encoding  I m not used to working with binary data

User · Answer

From the comments  by SET and Stefan Steiger  below the accepted answer  here is a quick summary of how to encode decode a string to from base64 without need of a library   str    The quick brown fox jumps over the lazy dog   b64   btoa unescape encodeURIComponent str     str   decodeURIComponent escape window atob b64       Demo   uses jQuery library  but not for encode decode    x000D   x000D  str    The quick brown fox jumps over the lazy dog   x000D   x000D     input   val str   x000D   x000D      btnConv   click function    x000D    var txt      input   val    x000D    var b64   btoa unescape encodeURIComponent txt     x000D       input   val b64   x000D        btnDeConv   show    x000D      x000D      btnDeConv   click function    x000D    var b64      input   val    x000D    var txt   decodeURIComponent escape window atob b64     x000D       input   val txt   x000D      x000D   btnDeConv display none   x000D   lt script src  https   ajax googleapis com ajax libs jquery 2 1 1 jquery min js  gt  lt  script gt  x000D   x000D   lt input type  text    gt  x000D   lt button id  btnConv  gt Convert lt  button gt  x000D   lt button id  btnDeConv  gt DeConvert lt  button gt  x000D   x000D   x000D

User · Answer

if you need to encode HTML image object  you can write simple function like   function getBase64Image img        var canvas   document createElement  canvas        canvas width   img width      canvas height   img height      var ctx   canvas getContext  2d        ctx drawImage img  0  0       var dataURL   canvas toDataURL  image png           escape data image prefix   return dataURL replace   data image   png jpg  base64                or just return dataURL      return dataURL       To get base64 of image by id   function getBase64ImageById id       return getBase64Image document getElementById id           more here

User · Answer

This question and it s answers pointed me to the right direction  Especially with unicode atob and btoa can not be used  vanilla  and these days EVERYTHING is unicode       Directly from Mozilla  two nice functions for this purpose  tested with unicode and html tags inside   function b64EncodeUnicode str        return btoa encodeURIComponent str  replace     0-9A-F  2   g  function match  p1            return String fromCharCode  0x    p1               b64EncodeUnicode       la mode        4pyTIMOgIGxhIG1vZGU   b64EncodeUnicode   n        Cg       function b64DecodeUnicode str        return decodeURIComponent Array prototype map call atob str   function c            return         00    c charCodeAt 0  toString 16   slice -2          join          b64DecodeUnicode  4pyTIMOgIGxhIG1vZGU              la mode  b64DecodeUnicode  Cg           n    These functions will perform lightning fast in comparison to raw base64 decoding using a custom javascript function as btoa and atob are executed outside the interpreter   If you can ignore old IE and old mobile phones  like iphone 3   this should be a good solution

User · Answer

I have re-wrote by hand  these encoding and decoding methods with the exception of the hexadecimal one into a modular format for cross-platform   browser compatibility and also with real private scoping  and uses btoa and atob if they exist due to speed rather than utilize its own encoding   https   gist github com Nijikokun 5192472  Usage   base64 encode    String      base64 decode    String       utf8 encode    String      utf8 decode    String

User · Answer

I d rather use the bas64 encode decode methods from CryptoJS  the most popular library for standard and secure cryptographic algorithms implemented in JavaScript using best practices and patterns

User · Answer

Internet Explorer 10      Define the string var string    Hello World        Encode the String var encodedString   btoa string   console log encodedString      Outputs   SGVsbG8gV29ybGQh      Decode the String var decodedString   atob encodedString   console log decodedString      Outputs   Hello World       Cross-Browser     Create Base64 Object var Base64   keyStr  ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789     encode function e  var t    var n r i s o u a var f 0 e Base64  utf8 encode e  while f lt e length  n e charCodeAt f    r e charCodeAt f    i e charCodeAt f    s n gt  gt 2 o  n amp 3  lt  lt 4 r gt  gt 4 u  r amp 15  lt  lt 2 i gt  gt 6 a i amp 63 if isNaN r   u a 64 else if isNaN i   a 64 t t this  keyStr charAt s  this  keyStr charAt o  this  keyStr charAt u  this  keyStr charAt a  return t  decode function e  var t    var n r i var s o u a var f 0 e e replace    A-Za-z0-9        g     while f lt e length  s this  keyStr indexOf e charAt f     o this  keyStr indexOf e charAt f     u this  keyStr indexOf e charAt f     a this  keyStr indexOf e charAt f     n s lt  lt 2 o gt  gt 4 r  o amp 15  lt  lt 4 u gt  gt 2 i  u amp 3  lt  lt 6 a t t String fromCharCode n  if u  64  t t String fromCharCode r  if a  64  t t String fromCharCode i   t Base64  utf8 decode t  return t   utf8 encode function e  e e replace   r n g   n   var t    for var n 0 n lt e length n    var r e charCodeAt n  if r lt 128  t  String fromCharCode r  else if r gt 127 amp  amp r lt 2048  t  String fromCharCode r gt  gt 6 192  t  String fromCharCode r amp 63 128  else t  String fromCharCode r gt  gt 12 224  t  String fromCharCode r gt  gt 6 amp 63 128  t  String fromCharCode r amp 63 128   return t   utf8 decode function e  var t    var n 0 var r c1 c2 0 while n lt e length  r e charCodeAt n  if r lt 128  t  String fromCharCode r  n   else if r gt 191 amp  amp r lt 224  c2 e charCodeAt n 1  t  String fromCharCode  r amp 31  lt  lt 6 c2 amp 63  n  2 else c2 e charCodeAt n 1  c3 e charCodeAt n 2  t  String fromCharCode  r amp 15  lt  lt 12  c2 amp 63  lt  lt 6 c3 amp 63  n  3  return t       Define the string var string    Hello World        Encode the String var encodedString   Base64 encode string   console log encodedString      Outputs   SGVsbG8gV29ybGQh      Decode the String var decodedString   Base64 decode encodedString   console log decodedString      Outputs   Hello World     jsFiddle    with Node js  Here is how you encode normal text to base64 in Node js     Buffer   requires a number  array or string as the first parameter  and an optional encoding type as the second parameter      Default is utf8  possible encoding types are ascii  utf8  ucs2  base64  binary  and hex var b   new Buffer  JavaScript       If we don t use toString    JavaScript assumes we want to convert the object to utf8     We can make it convert to other formats by passing the encoding type to toString    var s   b toString  base64      And here is how you decode base64 encoded strings   var b   new Buffer  SmF2YVNjcmlwdA      base64   var s   b toString        with Dojo js  To encode an array of bytes using dojox encoding base64   var str   dojox encoding base64 encode myByteArray     To decode a base64-encoded string   var bytes   dojox encoding base64 decode str      bower install angular-base64   lt script src  bower components angular-base64 angular-base64 js  gt  lt  script gt   angular      module  myApp     base64         controller  myController            base64     scope        function  base64   scope              scope encoded    base64 encode  a string             scope decoded    base64 decode  YSBzdHJpbmc

User · Answer

There s a couple of bugs in both implementations of  utf8 decode  c1 and c2 are assigned as global variables due to broken use of the var statement  and c3 is not initialized or declared at all   It works  but these variables will overwrite any existing ones with the same name outside this function   Here s a version that won t do this      private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   0  c1   0  c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c1   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c1  amp  63                i    2                    else               c1   utftext charCodeAt i 1               c2   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c1  amp  63   lt  lt  6     c2  amp  63                i    3                       return string

User · Answer

Well  if you are using dojo  it gives us direct way to encode or decode into base64   Try this -  To encode an array of bytes using dojox encoding base64   var str   dojox encoding base64 encode myByteArray     To decode a base64-encoded string   var bytes   dojox encoding base64 decode str

User · Answer

Contributing with a minified polyfill for window atob   window btoa that I m currently using    function   function t t  this message t var e  undefined   typeof exports exports this r  ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789     t prototype Error   t prototype name  InvalidCharacterError  e btoa   e btoa function e  for var o n a 0 i r c    e charAt 0 a    i     a 1  c  i charAt 63 amp o gt  gt 8-8  a 1    if n e charCodeAt a   75  n gt 255 throw new t   btoa  failed  The string to be encoded contains characters outside of the Latin1 range    o o lt  lt 8 n return c   e atob   e atob function e  if e e replace           1  e length 4 throw new t   atob  failed  The string to be decoded is not correctly encoded    for var o n a 0 i 0 c    n e charAt i     n amp  amp  o a 4 64 o n n a   4  c  String fromCharCode 255 amp o gt  gt  6 amp -2 a   0 n r indexOf n  return c

User · Answer

You can use btoa   and atob   to convert to and from base64 encoding  There appears to be some confusion in the comments regarding what these functions accept return  so     btoa   accepts a    string    where each character represents an 8-bit byte     if you pass a string containing characters that can   t be represented in 8 bits  it will probably break  This isn   t a problem if you   re actually treating the string as a byte array  but if you   re trying to do something else then you   ll have to encode it first   atob   returns a    string    where each character represents an 8-bit byte     that is  its value will be between 0 and 0xff  This does not mean it   s ASCII     presumably if you   re using this function at all  you expect to be working with binary data and not text    See also   How do I load binary image data using Javascript and XMLHttpRequest    Most comments here are outdated  You can probably use both btoa   and atob    unless you support really outdated browsers  Check here   https   caniuse com  search atob https   caniuse com  search btoa

User · Answer

You can use btoa  to base-64  and atob  from base-64     For IE 9 and below  try the jquery-base64 plugin     base64 encode  this is a test      base64 decode  dGhpcyBpcyBhIHRlc3Q

User · Answer

Use js-base64 library as     btoa   doesn t work with emojis    x000D   x000D  var str    I was funny    x000D  console log  Original string    str   x000D   x000D  var encodedStr   Base64 encode str  x000D  console log  Encoded string    encodedStr   x000D   x000D  var decodedStr   Base64 decode encodedStr  x000D  console log  Decoded string    decodedStr   x000D   lt script src  https   cdn jsdelivr net npm js-base64 2 5 2 base64 min js  gt  lt  script gt  x000D   x000D   x000D

User · Answer

From the comments  by SET and Stefan Steiger  below the accepted answer  here is a quick summary of how to encode decode a string to from base64 without need of a library   str    The quick brown fox jumps over the lazy dog   b64   btoa unescape encodeURIComponent str     str   decodeURIComponent escape window atob b64       Demo   uses jQuery library  but not for encode decode    x000D   x000D  str    The quick brown fox jumps over the lazy dog   x000D   x000D     input   val str   x000D   x000D      btnConv   click function    x000D    var txt      input   val    x000D    var b64   btoa unescape encodeURIComponent txt     x000D       input   val b64   x000D        btnDeConv   show    x000D      x000D      btnDeConv   click function    x000D    var b64      input   val    x000D    var txt   decodeURIComponent escape window atob b64     x000D       input   val txt   x000D      x000D   btnDeConv display none   x000D   lt script src  https   ajax googleapis com ajax libs jquery 2 1 1 jquery min js  gt  lt  script gt  x000D   x000D   lt input type  text    gt  x000D   lt button id  btnConv  gt Convert lt  button gt  x000D   lt button id  btnDeConv  gt DeConvert lt  button gt  x000D   x000D   x000D

User · Answer

You can use btoa   and atob   to convert to and from base64 encoding  There appears to be some confusion in the comments regarding what these functions accept return  so     btoa   accepts a    string    where each character represents an 8-bit byte     if you pass a string containing characters that can   t be represented in 8 bits  it will probably break  This isn   t a problem if you   re actually treating the string as a byte array  but if you   re trying to do something else then you   ll have to encode it first   atob   returns a    string    where each character represents an 8-bit byte     that is  its value will be between 0 and 0xff  This does not mean it   s ASCII     presumably if you   re using this function at all  you expect to be working with binary data and not text    See also   How do I load binary image data using Javascript and XMLHttpRequest    Most comments here are outdated  You can probably use both btoa   and atob    unless you support really outdated browsers  Check here   https   caniuse com  search atob https   caniuse com  search btoa

User · Answer

I needed encoding of an UTF-8 string as base64 for a project of mine  Most of the answers here don t seem to properly handle UTF-16 surrogate pairs when converting to UTF-8 so  for completion sake  I will post my solution   function strToUTF8Base64 str         function decodeSurrogatePair hi  lo            var resultChar   0x010000          resultChar    lo - 0xDC00          resultChar     hi - 0xD800   lt  lt  10          return resultChar             var bytes    0  0  0       var byteIndex   0      var result            function output s            result push s              function emitBase64              var digits                    ABCDEFGHIJKLMNOPQRSTUVWXYZ                     abcdefghijklmnopqrstuvwxyz                     0123456789              function toDigit value                return digits value                         --Byte 0--    --Byte 1--    --Byte 2--            1111  1122    2222  3333    3344  4444          var d1   toDigit bytes 0   gt  gt  2           var d2   toDigit                bytes 0   amp  0x03   lt  lt  4                 bytes 1   gt  gt  4            var d3   toDigit                bytes 1   amp  0x0F   lt  lt  2                 bytes 2   gt  gt  6            var d4   toDigit              bytes 2   amp  0x3F            if  byteIndex     1                output d1   d2                            else if  byteIndex     2                output d1   d2   d3                           else               output d1   d2   d3   d4                        function emit chr            bytes byteIndex      chr          if  byteIndex    3                emitBase64                bytes 0    0              bytes 1    0              bytes 2    0              byteIndex   0                       function emitLast             if  byteIndex  gt  0                emitBase64                            Converts the string to UTF8       var i  chr      var hi  lo      for  i   0  i  lt  str length  i              chr   str charCodeAt i               Test and decode surrogate pairs in the string         if  chr  gt   0xD800  amp  amp  chr  lt   0xDBFF                hi   chr              lo   str charCodeAt i   1               if  lo  gt   0xDC00  amp  amp  lo  lt   0xDFFF                    chr   decodeSurrogatePair hi  lo                   i                                        Encode the character as UTF-8          if  chr  lt  0x80                emit chr                     else if  chr  lt  0x0800                emit  chr  gt  gt  6    0xC0               emit   chr  gt  gt  0   amp  0x3F    0x80                     else if  chr  lt  0x10000                emit  chr  gt  gt  12    0xE0               emit   chr  gt  gt   6   amp  0x3F    0x80               emit   chr  gt  gt   0   amp  0x3F    0x80                     else if  chr  lt  0x110000                emit  chr  gt  gt  18    0xF0               emit   chr  gt  gt  12   amp  0x3F    0x80               emit   chr  gt  gt   6   amp  0x3F    0x80               emit   chr  gt  gt   0   amp  0x3F    0x80                        emitLast         return result join          Note that the code is not thoroughly tested  I tested some inputs  including things like strToUTF8Base64         and compared with the output of an online encoding tool  https   www base64encode org

User · Answer

Sunny s code is great except it breaks in IE7 because of references to  this     Fixed by replacing such references with  Base64    var Base64        private property  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789          public method for encoding encode   function  input        var output           var chr1  chr2  chr3  enc1  enc2  enc3  enc4      var i   0       input   Base64  utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output   output           Base64  keyStr charAt enc1    Base64  keyStr charAt enc2            Base64  keyStr charAt enc3    Base64  keyStr charAt enc4               return output         public method for decoding decode   function  input        var output           var chr1  chr2  chr3      var enc1  enc2  enc3  enc4      var i   0       input   input replace    A-Za-z0-9        g            while  i  lt  input length             enc1   Base64  keyStr indexOf input charAt i              enc2   Base64  keyStr indexOf input charAt i              enc3   Base64  keyStr indexOf input charAt i              enc4   Base64  keyStr indexOf input charAt i               chr1    enc1  lt  lt  2     enc2  gt  gt  4           chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2           chr3     enc3  amp  3   lt  lt  6    enc4           output   output   String fromCharCode chr1            if  enc3    64                output   output   String fromCharCode chr2                     if  enc4    64                output   output   String fromCharCode chr3                         output   Base64  utf8 decode output        return output          private method for UTF-8 encoding  utf8 encode   function  string        string   string replace   r n g   n        var utftext            for  var n   0  n  lt  string length  n               var c   string charCodeAt n            if  c  lt  128                utftext    String fromCharCode c                     else if  c  gt  127   amp  amp   c  lt  2048                 utftext    String fromCharCode  c  gt  gt  6    192               utftext    String fromCharCode  c  amp  63    128                     else               utftext    String fromCharCode  c  gt  gt  12    224               utftext    String fromCharCode   c  gt  gt  6   amp  63    128               utftext    String fromCharCode  c  amp  63    128                         return utftext         private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   c1   c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c2   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                i    2                    else               c2   utftext charCodeAt i 1               c3   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                i    3                       return string

User · Answer

Please note that this is not suitable for raw Unicode strings  See Unicode section here   Syntax for encoding  var encodedData   window btoa stringToEncode    Syntax for decoding  var decodedData   window atob encodedData

User · Answer

To make a Base64 encoded String URL friendly  in JavaScript you could do something like this      if this is your Base64 encoded string var str    VGhpcyBpcyBhbiBhd2Vzb21lIHNjcmlwdA          make URL friendly  str   str replace     g   -   replace     g       replace                  reverse to original encoding str    str          slice 0  str length    str length   4    str   str replace  - g       replace    g          See also this Fiddle  http   jsfiddle net magikMaker 7bjaT

User · Answer

I needed encoding of an UTF-8 string as base64 for a project of mine  Most of the answers here don t seem to properly handle UTF-16 surrogate pairs when converting to UTF-8 so  for completion sake  I will post my solution   function strToUTF8Base64 str         function decodeSurrogatePair hi  lo            var resultChar   0x010000          resultChar    lo - 0xDC00          resultChar     hi - 0xD800   lt  lt  10          return resultChar             var bytes    0  0  0       var byteIndex   0      var result            function output s            result push s              function emitBase64              var digits                    ABCDEFGHIJKLMNOPQRSTUVWXYZ                     abcdefghijklmnopqrstuvwxyz                     0123456789              function toDigit value                return digits value                         --Byte 0--    --Byte 1--    --Byte 2--            1111  1122    2222  3333    3344  4444          var d1   toDigit bytes 0   gt  gt  2           var d2   toDigit                bytes 0   amp  0x03   lt  lt  4                 bytes 1   gt  gt  4            var d3   toDigit                bytes 1   amp  0x0F   lt  lt  2                 bytes 2   gt  gt  6            var d4   toDigit              bytes 2   amp  0x3F            if  byteIndex     1                output d1   d2                            else if  byteIndex     2                output d1   d2   d3                           else               output d1   d2   d3   d4                        function emit chr            bytes byteIndex      chr          if  byteIndex    3                emitBase64                bytes 0    0              bytes 1    0              bytes 2    0              byteIndex   0                       function emitLast             if  byteIndex  gt  0                emitBase64                            Converts the string to UTF8       var i  chr      var hi  lo      for  i   0  i  lt  str length  i              chr   str charCodeAt i               Test and decode surrogate pairs in the string         if  chr  gt   0xD800  amp  amp  chr  lt   0xDBFF                hi   chr              lo   str charCodeAt i   1               if  lo  gt   0xDC00  amp  amp  lo  lt   0xDFFF                    chr   decodeSurrogatePair hi  lo                   i                                        Encode the character as UTF-8          if  chr  lt  0x80                emit chr                     else if  chr  lt  0x0800                emit  chr  gt  gt  6    0xC0               emit   chr  gt  gt  0   amp  0x3F    0x80                     else if  chr  lt  0x10000                emit  chr  gt  gt  12    0xE0               emit   chr  gt  gt   6   amp  0x3F    0x80               emit   chr  gt  gt   0   amp  0x3F    0x80                     else if  chr  lt  0x110000                emit  chr  gt  gt  18    0xF0               emit   chr  gt  gt  12   amp  0x3F    0x80               emit   chr  gt  gt   6   amp  0x3F    0x80               emit   chr  gt  gt   0   amp  0x3F    0x80                        emitLast         return result join          Note that the code is not thoroughly tested  I tested some inputs  including things like strToUTF8Base64         and compared with the output of an online encoding tool  https   www base64encode org

User · Answer

Here is an AngularJS Factory version of  user850789 s one    use strict    var ProjectNameBase64Factory   angular module  project name factories base64         ProjectNameBase64Factory factory  Base64   function          var Base64                private property          keyStr   ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789                  public method for encoding         encode  function  input                var output                   var chr1  chr2  chr3  enc1  enc2  enc3  enc4              var i   0               input   Base64  utf8 encode input                while  i  lt  input length                     chr1   input charCodeAt i                     chr2   input charCodeAt i                     chr3   input charCodeAt i                      enc1   chr1  gt  gt  2                  enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4                   enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6                   enc4   chr3  amp  63                   if  isNaN chr2                         enc3   enc4   64                    else if  isNaN chr3                         enc4   64                                     output   output                            Base64  keyStr charAt enc1    Base64  keyStr charAt enc2                             Base64  keyStr charAt enc3    Base64  keyStr charAt enc4                               return output                         public method for decoding         decode  function  input                var output                   var chr1  chr2  chr3              var enc1  enc2  enc3  enc4              var i   0               input   input replace    A-Za-z0-9        g                    while  i  lt  input length                     enc1   Base64  keyStr indexOf input charAt i                      enc2   Base64  keyStr indexOf input charAt i                      enc3   Base64  keyStr indexOf input charAt i                      enc4   Base64  keyStr indexOf input charAt i                       chr1    enc1  lt  lt  2     enc2  gt  gt  4                   chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2                   chr3     enc3  amp  3   lt  lt  6    enc4                   output   output   String fromCharCode chr1                    if  enc3    64                        output   output   String fromCharCode chr2                                     if  enc4    64                        output   output   String fromCharCode chr3                                                 output   Base64  utf8 decode output                return output                          private method for UTF-8 encoding          utf8 encode  function  string                string   string replace   r n g    n                var utftext                    for  var n   0  n  lt  string length  n                       var c   string charCodeAt n                    if  c  lt  128                        utftext    String fromCharCode c                                     else if   c  gt  127   amp  amp   c  lt  2048                         utftext    String fromCharCode  c  gt  gt  6    192                       utftext    String fromCharCode  c  amp  63    128                                     else                       utftext    String fromCharCode  c  gt  gt  12    224                       utftext    String fromCharCode   c  gt  gt  6   amp  63    128                       utftext    String fromCharCode  c  amp  63    128                                                 return utftext                         private method for UTF-8 decoding          utf8 decode  function  utftext                var string                   var i   0              var c   0  c2   0  c3   0               while  i  lt  utftext length                     c   utftext charCodeAt i                    if  c  lt  128                        string    String fromCharCode c                       i                                      else if   c  gt  191   amp  amp   c  lt  224                         c2   utftext charCodeAt i   1                       string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                        i    2                                    else                       c2   utftext charCodeAt i   1                       c3   utftext charCodeAt i   2                       string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                        i    3                                               return string                       return Base64

User · Answer

For newer browsers to encode Uint8Array to string  and decode string to Uint8Array   const base64         decode  s   gt  Uint8Array from atob s   c   gt  c charCodeAt 0        encode  b   gt  btoa String fromCharCode    new Uint8Array b         For Node js you can use the following to encode string  Buffer  or Uint8Array to string  and decode from string  Buffer  or Uint8Array to Buffer   const base64         decode  s   gt  Buffer from s   base64        encode  b   gt  Buffer from b  toString  base64

User · Answer

To make a Base64 encoded String URL friendly  in JavaScript you could do something like this      if this is your Base64 encoded string var str    VGhpcyBpcyBhbiBhd2Vzb21lIHNjcmlwdA          make URL friendly  str   str replace     g   -   replace     g       replace                  reverse to original encoding str    str          slice 0  str length    str length   4    str   str replace  - g       replace    g          See also this Fiddle  http   jsfiddle net magikMaker 7bjaT

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There s a couple of bugs in both implementations of  utf8 decode  c1 and c2 are assigned as global variables due to broken use of the var statement  and c3 is not initialized or declared at all   It works  but these variables will overwrite any existing ones with the same name outside this function   Here s a version that won t do this      private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   0  c1   0  c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c1   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c1  amp  63                i    2                    else               c1   utftext charCodeAt i 1               c2   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c1  amp  63   lt  lt  6     c2  amp  63                i    3                       return string

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From here            Base64 encode   decode    http   www webtoolkit info        var Base64         private property  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789          public method for encoding encode   function  input        var output           var chr1  chr2  chr3  enc1  enc2  enc3  enc4      var i   0       input   Base64  utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output   output           this  keyStr charAt enc1    this  keyStr charAt enc2            this  keyStr charAt enc3    this  keyStr charAt enc4               return output         public method for decoding decode   function  input        var output           var chr1  chr2  chr3      var enc1  enc2  enc3  enc4      var i   0       input   input replace    A-Za-z0-9        g            while  i  lt  input length             enc1   this  keyStr indexOf input charAt i              enc2   this  keyStr indexOf input charAt i              enc3   this  keyStr indexOf input charAt i              enc4   this  keyStr indexOf input charAt i               chr1    enc1  lt  lt  2     enc2  gt  gt  4           chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2           chr3     enc3  amp  3   lt  lt  6    enc4           output   output   String fromCharCode chr1            if  enc3    64                output   output   String fromCharCode chr2                     if  enc4    64                output   output   String fromCharCode chr3                         output   Base64  utf8 decode output        return output          private method for UTF-8 encoding  utf8 encode   function  string        string   string replace   r n g   n        var utftext            for  var n   0  n  lt  string length  n               var c   string charCodeAt n            if  c  lt  128                utftext    String fromCharCode c                     else if  c  gt  127   amp  amp   c  lt  2048                 utftext    String fromCharCode  c  gt  gt  6    192               utftext    String fromCharCode  c  amp  63    128                     else               utftext    String fromCharCode  c  gt  gt  12    224               utftext    String fromCharCode   c  gt  gt  6   amp  63    128               utftext    String fromCharCode  c  amp  63    128                         return utftext         private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   c1   c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c2   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                i    2                    else               c2   utftext charCodeAt i 1               c3   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                i    3                        return string         Also  search on  javascript base64 encoding  turns a lot of other options  the above was the first one

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You can use window btoa and window atob     const encoded   window btoa  Alireza Dezfoolian       encode a string const decoded   window atob encoded      decode the string   Probably using the way which MDN is can do your job the best    Also accepting unicode    using these two simple functions      ucs-2 string to base64 encoded ascii function utoa str        return window btoa unescape encodeURIComponent str          base64 encoded ascii to ucs-2 string function atou str        return decodeURIComponent escape window atob str          Usage  utoa       la mode       4pyTIMOgIGxhIG1vZGU  atou  4pyTIMOgIGxhIG1vZGU              la mode   utoa  I  u2661 Unicode        SSDimaEgVW5pY29kZSE  atou  SSDimaEgVW5pY29kZSE         I   Unicode

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Internet Explorer 10      Define the string var string    Hello World        Encode the String var encodedString   btoa string   console log encodedString      Outputs   SGVsbG8gV29ybGQh      Decode the String var decodedString   atob encodedString   console log decodedString      Outputs   Hello World       Cross-Browser     Create Base64 Object var Base64   keyStr  ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789     encode function e  var t    var n r i s o u a var f 0 e Base64  utf8 encode e  while f lt e length  n e charCodeAt f    r e charCodeAt f    i e charCodeAt f    s n gt  gt 2 o  n amp 3  lt  lt 4 r gt  gt 4 u  r amp 15  lt  lt 2 i gt  gt 6 a i amp 63 if isNaN r   u a 64 else if isNaN i   a 64 t t this  keyStr charAt s  this  keyStr charAt o  this  keyStr charAt u  this  keyStr charAt a  return t  decode function e  var t    var n r i var s o u a var f 0 e e replace    A-Za-z0-9        g     while f lt e length  s this  keyStr indexOf e charAt f     o this  keyStr indexOf e charAt f     u this  keyStr indexOf e charAt f     a this  keyStr indexOf e charAt f     n s lt  lt 2 o gt  gt 4 r  o amp 15  lt  lt 4 u gt  gt 2 i  u amp 3  lt  lt 6 a t t String fromCharCode n  if u  64  t t String fromCharCode r  if a  64  t t String fromCharCode i   t Base64  utf8 decode t  return t   utf8 encode function e  e e replace   r n g   n   var t    for var n 0 n lt e length n    var r e charCodeAt n  if r lt 128  t  String fromCharCode r  else if r gt 127 amp  amp r lt 2048  t  String fromCharCode r gt  gt 6 192  t  String fromCharCode r amp 63 128  else t  String fromCharCode r gt  gt 12 224  t  String fromCharCode r gt  gt 6 amp 63 128  t  String fromCharCode r amp 63 128   return t   utf8 decode function e  var t    var n 0 var r c1 c2 0 while n lt e length  r e charCodeAt n  if r lt 128  t  String fromCharCode r  n   else if r gt 191 amp  amp r lt 224  c2 e charCodeAt n 1  t  String fromCharCode  r amp 31  lt  lt 6 c2 amp 63  n  2 else c2 e charCodeAt n 1  c3 e charCodeAt n 2  t  String fromCharCode  r amp 15  lt  lt 12  c2 amp 63  lt  lt 6 c3 amp 63  n  3  return t       Define the string var string    Hello World        Encode the String var encodedString   Base64 encode string   console log encodedString      Outputs   SGVsbG8gV29ybGQh      Decode the String var decodedString   Base64 decode encodedString   console log decodedString      Outputs   Hello World     jsFiddle    with Node js  Here is how you encode normal text to base64 in Node js     Buffer   requires a number  array or string as the first parameter  and an optional encoding type as the second parameter      Default is utf8  possible encoding types are ascii  utf8  ucs2  base64  binary  and hex var b   new Buffer  JavaScript       If we don t use toString    JavaScript assumes we want to convert the object to utf8     We can make it convert to other formats by passing the encoding type to toString    var s   b toString  base64      And here is how you decode base64 encoded strings   var b   new Buffer  SmF2YVNjcmlwdA      base64   var s   b toString        with Dojo js  To encode an array of bytes using dojox encoding base64   var str   dojox encoding base64 encode myByteArray     To decode a base64-encoded string   var bytes   dojox encoding base64 decode str      bower install angular-base64   lt script src  bower components angular-base64 angular-base64 js  gt  lt  script gt   angular      module  myApp     base64         controller  myController            base64     scope        function  base64   scope              scope encoded    base64 encode  a string             scope decoded    base64 decode  YSBzdHJpbmc

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I  1 ed Sunny s answer  but I wanted to contribute back a few changes I made for my own project in case anyone should find it useful  Basically I ve just cleaned up the original code a little so JSLint doesn t complain quite as much  and I made the methods marked as private in the comments actually private  I also added two methods I needed in my own project  namely decodeToHex and encodeFromHex   The code   var Base64    function          use strict        var  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789           var  utf8 encode   function  string             var utftext       c  n           string   string replace   r n g   n             for  n   0  n  lt  string length  n                   c   string charCodeAt n                if  c  lt  128                     utftext    String fromCharCode c                  else if  c  gt  127   amp  amp   c  lt  2048                      utftext    String fromCharCode  c  gt  gt  6    192                   utftext    String fromCharCode  c  amp  63    128                  else                    utftext    String fromCharCode  c  gt  gt  12    224                   utftext    String fromCharCode   c  gt  gt  6   amp  63    128                   utftext    String fromCharCode  c  amp  63    128                                      return utftext              var  utf8 decode   function  utftext            var string       i   0  c   0  c1   0  c2   0           while   i  lt  utftext length                  c   utftext charCodeAt i                if  c  lt  128                     string    String fromCharCode c                   i                   else if  c  gt  191   amp  amp   c  lt  224                      c1   utftext charCodeAt i 1                   string    String fromCharCode   c  amp  31   lt  lt  6     c1  amp  63                    i    2                 else                    c1   utftext charCodeAt i 1                   c2   utftext charCodeAt i 2                   string    String fromCharCode   c  amp  15   lt  lt  12      c1  amp  63   lt  lt  6     c2  amp  63                    i    3                                     return string              var  hexEncode   function input            var output       i           for i   0  i  lt  input length  i                  output    input charCodeAt i  toString 16                      return output              var  hexDecode   function input            var output       i           if input length   2  gt  0                input    0    input                     for i   0  i  lt  input length  i   i   2                output    String fromCharCode parseInt input charAt i    input charAt i   1   16                       return output              var encode   function  input            var output       chr1  chr2  chr3  enc1  enc2  enc3  enc4  i   0           input    utf8 encode input            while  i  lt  input length                 chr1   input charCodeAt i                 chr2   input charCodeAt i                 chr3   input charCodeAt i                  enc1   chr1  gt  gt  2              enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4               enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6               enc4   chr3  amp  63               if  isNaN chr2                     enc3   enc4   64                else if  isNaN chr3                     enc4   64                             output     keyStr charAt enc1               output     keyStr charAt enc2               output     keyStr charAt enc3               output     keyStr charAt enc4                       return output              var decode   function  input            var output       chr1  chr2  chr3  enc1  enc2  enc3  enc4  i   0           input   input replace    A-Za-z0-9        g                while  i  lt  input length                 enc1    keyStr indexOf input charAt i                  enc2    keyStr indexOf input charAt i                  enc3    keyStr indexOf input charAt i                  enc4    keyStr indexOf input charAt i                   chr1    enc1  lt  lt  2     enc2  gt  gt  4               chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2               chr3     enc3  amp  3   lt  lt  6    enc4               output    String fromCharCode chr1                if  enc3     64                    output    String fromCharCode chr2                             if  enc4     64                    output    String fromCharCode chr3                                     return  utf8 decode output               var decodeToHex   function input            return  hexEncode decode input                var encodeFromHex   function input            return encode  hexDecode input                return            encode   encode           decode   decode           decodeToHex   decodeToHex           encodeFromHex   encodeFromHex

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While a bit more work  if you want a high performance native solution there are some HTML5 functions you can use   If you can get your data into a Blob  then you can use the FileReader readAsDataURL   function to get a data    URL and chop off the front of it to get at the base64 data   You may have to do further processing however to urldecode the data  as I m not sure whether   characters are escaped or not for the data    URL  but this should be pretty trivial

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if you need to encode HTML image object  you can write simple function like   function getBase64Image img        var canvas   document createElement  canvas        canvas width   img width      canvas height   img height      var ctx   canvas getContext  2d        ctx drawImage img  0  0       var dataURL   canvas toDataURL  image png           escape data image prefix   return dataURL replace   data image   png jpg  base64                or just return dataURL      return dataURL       To get base64 of image by id   function getBase64ImageById id       return getBase64Image document getElementById id           more here

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You can use btoa   and atob   to convert to and from base64 encoding  There appears to be some confusion in the comments regarding what these functions accept return  so     btoa   accepts a    string    where each character represents an 8-bit byte     if you pass a string containing characters that can   t be represented in 8 bits  it will probably break  This isn   t a problem if you   re actually treating the string as a byte array  but if you   re trying to do something else then you   ll have to encode it first   atob   returns a    string    where each character represents an 8-bit byte     that is  its value will be between 0 and 0xff  This does not mean it   s ASCII     presumably if you   re using this function at all  you expect to be working with binary data and not text    See also   How do I load binary image data using Javascript and XMLHttpRequest    Most comments here are outdated  You can probably use both btoa   and atob    unless you support really outdated browsers  Check here   https   caniuse com  search atob https   caniuse com  search btoa

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Sunny s code is great except it breaks in IE7 because of references to  this     Fixed by replacing such references with  Base64    var Base64        private property  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789          public method for encoding encode   function  input        var output           var chr1  chr2  chr3  enc1  enc2  enc3  enc4      var i   0       input   Base64  utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output   output           Base64  keyStr charAt enc1    Base64  keyStr charAt enc2            Base64  keyStr charAt enc3    Base64  keyStr charAt enc4               return output         public method for decoding decode   function  input        var output           var chr1  chr2  chr3      var enc1  enc2  enc3  enc4      var i   0       input   input replace    A-Za-z0-9        g            while  i  lt  input length             enc1   Base64  keyStr indexOf input charAt i              enc2   Base64  keyStr indexOf input charAt i              enc3   Base64  keyStr indexOf input charAt i              enc4   Base64  keyStr indexOf input charAt i               chr1    enc1  lt  lt  2     enc2  gt  gt  4           chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2           chr3     enc3  amp  3   lt  lt  6    enc4           output   output   String fromCharCode chr1            if  enc3    64                output   output   String fromCharCode chr2                     if  enc4    64                output   output   String fromCharCode chr3                         output   Base64  utf8 decode output        return output          private method for UTF-8 encoding  utf8 encode   function  string        string   string replace   r n g   n        var utftext            for  var n   0  n  lt  string length  n               var c   string charCodeAt n            if  c  lt  128                utftext    String fromCharCode c                     else if  c  gt  127   amp  amp   c  lt  2048                 utftext    String fromCharCode  c  gt  gt  6    192               utftext    String fromCharCode  c  amp  63    128                     else               utftext    String fromCharCode  c  gt  gt  12    224               utftext    String fromCharCode   c  gt  gt  6   amp  63    128               utftext    String fromCharCode  c  amp  63    128                         return utftext         private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   c1   c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c2   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                i    2                    else               c2   utftext charCodeAt i 1               c3   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                i    3                       return string

User · Answer

You can use btoa  to base-64  and atob  from base-64     For IE 9 and below  try the jquery-base64 plugin     base64 encode  this is a test      base64 decode  dGhpcyBpcyBhIHRlc3Q

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From here            Base64 encode   decode    http   www webtoolkit info        var Base64         private property  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789          public method for encoding encode   function  input        var output           var chr1  chr2  chr3  enc1  enc2  enc3  enc4      var i   0       input   Base64  utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output   output           this  keyStr charAt enc1    this  keyStr charAt enc2            this  keyStr charAt enc3    this  keyStr charAt enc4               return output         public method for decoding decode   function  input        var output           var chr1  chr2  chr3      var enc1  enc2  enc3  enc4      var i   0       input   input replace    A-Za-z0-9        g            while  i  lt  input length             enc1   this  keyStr indexOf input charAt i              enc2   this  keyStr indexOf input charAt i              enc3   this  keyStr indexOf input charAt i              enc4   this  keyStr indexOf input charAt i               chr1    enc1  lt  lt  2     enc2  gt  gt  4           chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2           chr3     enc3  amp  3   lt  lt  6    enc4           output   output   String fromCharCode chr1            if  enc3    64                output   output   String fromCharCode chr2                     if  enc4    64                output   output   String fromCharCode chr3                         output   Base64  utf8 decode output        return output          private method for UTF-8 encoding  utf8 encode   function  string        string   string replace   r n g   n        var utftext            for  var n   0  n  lt  string length  n               var c   string charCodeAt n            if  c  lt  128                utftext    String fromCharCode c                     else if  c  gt  127   amp  amp   c  lt  2048                 utftext    String fromCharCode  c  gt  gt  6    192               utftext    String fromCharCode  c  amp  63    128                     else               utftext    String fromCharCode  c  gt  gt  12    224               utftext    String fromCharCode   c  gt  gt  6   amp  63    128               utftext    String fromCharCode  c  amp  63    128                         return utftext         private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   c1   c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c2   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                i    2                    else               c2   utftext charCodeAt i 1               c3   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                i    3                        return string         Also  search on  javascript base64 encoding  turns a lot of other options  the above was the first one

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From here            Base64 encode   decode    http   www webtoolkit info        var Base64         private property  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789          public method for encoding encode   function  input        var output           var chr1  chr2  chr3  enc1  enc2  enc3  enc4      var i   0       input   Base64  utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output   output           this  keyStr charAt enc1    this  keyStr charAt enc2            this  keyStr charAt enc3    this  keyStr charAt enc4               return output         public method for decoding decode   function  input        var output           var chr1  chr2  chr3      var enc1  enc2  enc3  enc4      var i   0       input   input replace    A-Za-z0-9        g            while  i  lt  input length             enc1   this  keyStr indexOf input charAt i              enc2   this  keyStr indexOf input charAt i              enc3   this  keyStr indexOf input charAt i              enc4   this  keyStr indexOf input charAt i               chr1    enc1  lt  lt  2     enc2  gt  gt  4           chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2           chr3     enc3  amp  3   lt  lt  6    enc4           output   output   String fromCharCode chr1            if  enc3    64                output   output   String fromCharCode chr2                     if  enc4    64                output   output   String fromCharCode chr3                         output   Base64  utf8 decode output        return output          private method for UTF-8 encoding  utf8 encode   function  string        string   string replace   r n g   n        var utftext            for  var n   0  n  lt  string length  n               var c   string charCodeAt n            if  c  lt  128                utftext    String fromCharCode c                     else if  c  gt  127   amp  amp   c  lt  2048                 utftext    String fromCharCode  c  gt  gt  6    192               utftext    String fromCharCode  c  amp  63    128                     else               utftext    String fromCharCode  c  gt  gt  12    224               utftext    String fromCharCode   c  gt  gt  6   amp  63    128               utftext    String fromCharCode  c  amp  63    128                         return utftext         private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   c1   c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c2   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                i    2                    else               c2   utftext charCodeAt i 1               c3   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                i    3                        return string         Also  search on  javascript base64 encoding  turns a lot of other options  the above was the first one

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Use js-base64 library as     btoa   doesn t work with emojis    x000D   x000D  var str    I was funny    x000D  console log  Original string    str   x000D   x000D  var encodedStr   Base64 encode str  x000D  console log  Encoded string    encodedStr   x000D   x000D  var decodedStr   Base64 decode encodedStr  x000D  console log  Decoded string    decodedStr   x000D   lt script src  https   cdn jsdelivr net npm js-base64 2 5 2 base64 min js  gt  lt  script gt  x000D   x000D   x000D

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I d rather use the bas64 encode decode methods from CryptoJS  the most popular library for standard and secure cryptographic algorithms implemented in JavaScript using best practices and patterns

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Please note that this is not suitable for raw Unicode strings  See Unicode section here   Syntax for encoding  var encodedData   window btoa stringToEncode    Syntax for decoding  var decodedData   window atob encodedData

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I  1 ed Sunny s answer  but I wanted to contribute back a few changes I made for my own project in case anyone should find it useful  Basically I ve just cleaned up the original code a little so JSLint doesn t complain quite as much  and I made the methods marked as private in the comments actually private  I also added two methods I needed in my own project  namely decodeToHex and encodeFromHex   The code   var Base64    function          use strict        var  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789           var  utf8 encode   function  string             var utftext       c  n           string   string replace   r n g   n             for  n   0  n  lt  string length  n                   c   string charCodeAt n                if  c  lt  128                     utftext    String fromCharCode c                  else if  c  gt  127   amp  amp   c  lt  2048                      utftext    String fromCharCode  c  gt  gt  6    192                   utftext    String fromCharCode  c  amp  63    128                  else                    utftext    String fromCharCode  c  gt  gt  12    224                   utftext    String fromCharCode   c  gt  gt  6   amp  63    128                   utftext    String fromCharCode  c  amp  63    128                                      return utftext              var  utf8 decode   function  utftext            var string       i   0  c   0  c1   0  c2   0           while   i  lt  utftext length                  c   utftext charCodeAt i                if  c  lt  128                     string    String fromCharCode c                   i                   else if  c  gt  191   amp  amp   c  lt  224                      c1   utftext charCodeAt i 1                   string    String fromCharCode   c  amp  31   lt  lt  6     c1  amp  63                    i    2                 else                    c1   utftext charCodeAt i 1                   c2   utftext charCodeAt i 2                   string    String fromCharCode   c  amp  15   lt  lt  12      c1  amp  63   lt  lt  6     c2  amp  63                    i    3                                     return string              var  hexEncode   function input            var output       i           for i   0  i  lt  input length  i                  output    input charCodeAt i  toString 16                      return output              var  hexDecode   function input            var output       i           if input length   2  gt  0                input    0    input                     for i   0  i  lt  input length  i   i   2                output    String fromCharCode parseInt input charAt i    input charAt i   1   16                       return output              var encode   function  input            var output       chr1  chr2  chr3  enc1  enc2  enc3  enc4  i   0           input    utf8 encode input            while  i  lt  input length                 chr1   input charCodeAt i                 chr2   input charCodeAt i                 chr3   input charCodeAt i                  enc1   chr1  gt  gt  2              enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4               enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6               enc4   chr3  amp  63               if  isNaN chr2                     enc3   enc4   64                else if  isNaN chr3                     enc4   64                             output     keyStr charAt enc1               output     keyStr charAt enc2               output     keyStr charAt enc3               output     keyStr charAt enc4                       return output              var decode   function  input            var output       chr1  chr2  chr3  enc1  enc2  enc3  enc4  i   0           input   input replace    A-Za-z0-9        g                while  i  lt  input length                 enc1    keyStr indexOf input charAt i                  enc2    keyStr indexOf input charAt i                  enc3    keyStr indexOf input charAt i                  enc4    keyStr indexOf input charAt i                   chr1    enc1  lt  lt  2     enc2  gt  gt  4               chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2               chr3     enc3  amp  3   lt  lt  6    enc4               output    String fromCharCode chr1                if  enc3     64                    output    String fromCharCode chr2                             if  enc4     64                    output    String fromCharCode chr3                                     return  utf8 decode output               var decodeToHex   function input            return  hexEncode decode input                var encodeFromHex   function input            return encode  hexDecode input                return            encode   encode           decode   decode           decodeToHex   decodeToHex           encodeFromHex   encodeFromHex

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Contributing with a minified polyfill for window atob   window btoa that I m currently using    function   function t t  this message t var e  undefined   typeof exports exports this r  ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789     t prototype Error   t prototype name  InvalidCharacterError  e btoa   e btoa function e  for var o n a 0 i r c    e charAt 0 a    i     a 1  c  i charAt 63 amp o gt  gt 8-8  a 1    if n e charCodeAt a   75  n gt 255 throw new t   btoa  failed  The string to be encoded contains characters outside of the Latin1 range    o o lt  lt 8 n return c   e atob   e atob function e  if e e replace           1  e length 4 throw new t   atob  failed  The string to be decoded is not correctly encoded    for var o n a 0 i 0 c    n e charAt i     n amp  amp  o a 4 64 o n n a   4  c  String fromCharCode 255 amp o gt  gt  6 amp -2 a   0 n r indexOf n  return c

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You can use btoa   atob   in browser  but some improvements required  as described here https   base64tool com uncaught-domexception-btoa-on-window  and there https   developer mozilla org en-US docs Web API WindowOrWorkerGlobalScope btoa for UTF strings support

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You can use btoa   atob   in browser  but some improvements required  as described here https   base64tool com uncaught-domexception-btoa-on-window  and there https   developer mozilla org en-US docs Web API WindowOrWorkerGlobalScope btoa for UTF strings support

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Here is a LIVE DEMO of atob   and btoa   JS built in functions    lt  DOCTYPE html gt   lt html gt     lt head gt       lt style gt        textarea          width 30           height 100px               lt  style gt       lt script gt           encode string to base64       function encode                   var txt   document getElementById  txt1   value          var result   btoa txt           document getElementById  txt2   value   result                   decode base64 back to original string       function decode                   var txt   document getElementById  txt3   value          var result   atob txt           document getElementById  txt4   value   result               lt  script gt     lt  head gt     lt body gt       lt div gt         lt textarea id  txt1  gt Some text to decode        lt  textarea gt       lt  div gt       lt div gt         lt input type  button  id  btnencode  value  Encode  onClick  encode     gt       lt  div gt       lt div gt         lt textarea id  txt2  gt         lt  textarea gt       lt  div gt       lt br  gt       lt div gt         lt textarea id  txt3  gt U29tZSB0ZXh0IHRvIGRlY29kZQ          lt  textarea gt       lt  div gt       lt div gt         lt input type  button  id  btndecode  value  Decode  onClick  decode     gt       lt  div gt       lt div gt         lt textarea id  txt4  gt         lt  textarea gt       lt  div gt     lt  body gt   lt  html gt

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JS without btoa middlestep  no lib  In question title you write about string conversion  but in question you talk about binary data  picture  so here is function which make proper conversion starting from PNG picture binary data  details and reversal conversion here     x000D   x000D  function bytesArrToBase64 arr      const abc    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789        base64 alphabet   const bin   n   gt  n toString 2  padStart 8 0      convert num to 8-bit binary string   const l   arr length   let result          for let i 0  i lt   l-1  3  i          let c1   i 3 1 gt  l     case when     is on end     let c2   i 3 2 gt  l     case when     is on end     let chunk   bin arr 3 i     bin c1  0 arr 3 i 1     bin c2  0 arr 3 i 2        let r   chunk match    1 6  g  map  x j   gt  j  3 amp  amp c2         j  2 amp  amp c1       abc    0b  x            result    r join             return result          TEST  const pic        PNG binary data     0x89  0x50  0x4e  0x47  0x0d  0x0a  0x1a  0x0a  0x00  0x00  0x00  0x0d      0x49  0x48  0x44  0x52  0x00  0x00  0x00  0x10  0x00  0x00  0x00  0x10      0x08  0x06  0x00  0x00  0x00  0x1f  0xf3  0xff  0x61  0x00  0x00  0x00      0x01  0x73  0x52  0x47  0x42  0x00  0xae  0xce  0x1c  0xe9  0x00  0x00      0x01  0x59  0x69  0x54  0x58  0x74  0x58  0x4d  0x4c  0x3a  0x63  0x6f      0x6d  0x2e  0x61  0x64  0x6f  0x62  0x65  0x2e  0x78  0x6d  0x70  0x00      0x00  0x00  0x00  0x00  0x3c  0x78  0x3a  0x78  0x6d  0x70  0x6d  0x65      0x74  0x61  0x20  0x78  0x6d  0x6c  0x6e  0x73  0x3a  0x78  0x3d  0x22      0x61  0x64  0x6f  0x62  0x65  0x3a  0x6e  0x73  0x3a  0x6d  0x65  0x74      0x61  0x2f  0x22  0x20  0x78  0x3a  0x78  0x6d  0x70  0x74  0x6b  0x3d      0x22  0x58  0x4d  0x50  0x20  0x43  0x6f  0x72  0x65  0x20  0x35  0x2e      0x34  0x2e  0x30  0x22  0x3e  0x0a  0x20  0x20  0x20  0x3c  0x72  0x64      0x66  0x3a  0x52  0x44  0x46  0x20  0x78  0x6d  0x6c  0x6e  0x73  0x3a      0x72  0x64  0x66  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0x33  0x8e  0xf9  0x75  0x8c      0x92  0xe0  0x34  0xe8  0x27  0x88  0xd9  0xf4  0x76  0xcf  0xb0  0xaa      0x45  0xb2  0x0e  0x4a  0xe4  0x94  0x39  0x59  0x0c  0x03  0x54  0x14      0x58  0xce  0xbb  0xea  0xdb  0xd1  0x3b  0x71  0x75  0xb9  0x9a  0xe2      0x7a  0x7d  0x36  0x3f  0xdf  0x4b  0x95  0x35  0x09  0x09  0xef  0x73      0xfc  0xfa  0x85  0x67  0x02  0x3e  0x59  0x55  0x31  0x89  0x31  0x56      0x8c  0x78  0xb6  0x04  0xda  0x23  0x01  0x01  0xc8  0x8c  0xe5  0x77      0x87  0xbb  0x65  0x02  0x24  0xa4  0xad  0x82  0xcb  0x4b  0x4c  0x64      0x59  0x14  0xa0  0x72  0x40  0x3f  0xbf  0xe6  0x68  0xb6  0x9f  0x75      0x08  0x63  0xc8  0x9a  0x09  0x02  0x25  0x32  0x34  0x48  0x7e  0xcc      0x7d  0x10  0xaf  0xa6  0xd5  0xd2  0x1a  0x3d  0x89  0x38  0xf5  0xf1      0x14  0xb4  0x69  0x6a  0x4d  0x15  0xf5  0xc9  0xf0  0x5c  0x1a  0x61      0x8a  0x75  0xd1  0xe8  0x3a  0x2c  0x41  0x5d  0x70  0x41  0x20  0x29      0xf9  0x9b  0xb1  0x37  0xc5  0x4d  0xfc  0x45  0x84  0x7d  0x08  0x8f      0x89  0x76  0x54  0xf1  0x1b  0x19  0x92  0xef  0x2c  0xbe  0x46  0x8e      0xa6  0x49  0x5e  0x61  0x89  0xe4  0x05  0x5e  0x4e  0xa4  0x5c  0x10      0x6e  0x9f  0xfc  0x5b  0x00  0x00  0x00  0x00  0x49  0x45  0x4e  0x44      0xae  0x42  0x60  0x82     let b64pic   bytesArrToBase64 pic   myPic src    data image png base64   b64pic  msg innerHTML    Base64 encoded pic data  lt br gt     b64pic  x000D  img   zoom  10  image-rendering  pixelated     msg   word-break  break-all    x000D   lt img id  myPic  gt   lt code id  msg  gt  lt  code gt  x000D   x000D   x000D

User · Answer

You can use btoa   and atob   to convert to and from base64 encoding  There appears to be some confusion in the comments regarding what these functions accept return  so     btoa   accepts a    string    where each character represents an 8-bit byte     if you pass a string containing characters that can   t be represented in 8 bits  it will probably break  This isn   t a problem if you   re actually treating the string as a byte array  but if you   re trying to do something else then you   ll have to encode it first   atob   returns a    string    where each character represents an 8-bit byte     that is  its value will be between 0 and 0xff  This does not mean it   s ASCII     presumably if you   re using this function at all  you expect to be working with binary data and not text    See also   How do I load binary image data using Javascript and XMLHttpRequest    Most comments here are outdated  You can probably use both btoa   and atob    unless you support really outdated browsers  Check here   https   caniuse com  search atob https   caniuse com  search btoa

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This question and it s answers pointed me to the right direction  Especially with unicode atob and btoa can not be used  vanilla  and these days EVERYTHING is unicode       Directly from Mozilla  two nice functions for this purpose  tested with unicode and html tags inside   function b64EncodeUnicode str        return btoa encodeURIComponent str  replace     0-9A-F  2   g  function match  p1            return String fromCharCode  0x    p1               b64EncodeUnicode       la mode        4pyTIMOgIGxhIG1vZGU   b64EncodeUnicode   n        Cg       function b64DecodeUnicode str        return decodeURIComponent Array prototype map call atob str   function c            return         00    c charCodeAt 0  toString 16   slice -2          join          b64DecodeUnicode  4pyTIMOgIGxhIG1vZGU              la mode  b64DecodeUnicode  Cg           n    These functions will perform lightning fast in comparison to raw base64 decoding using a custom javascript function as btoa and atob are executed outside the interpreter   If you can ignore old IE and old mobile phones  like iphone 3   this should be a good solution

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Well  if you are using dojo  it gives us direct way to encode or decode into base64   Try this -  To encode an array of bytes using dojox encoding base64   var str   dojox encoding base64 encode myByteArray     To decode a base64-encoded string   var bytes   dojox encoding base64 decode str

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I have re-wrote by hand  these encoding and decoding methods with the exception of the hexadecimal one into a modular format for cross-platform   browser compatibility and also with real private scoping  and uses btoa and atob if they exist due to speed rather than utilize its own encoding   https   gist github com Nijikokun 5192472  Usage   base64 encode    String      base64 decode    String       utf8 encode    String      utf8 decode    String

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From here            Base64 encode   decode    http   www webtoolkit info        var Base64         private property  keyStr    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789          public method for encoding encode   function  input        var output           var chr1  chr2  chr3  enc1  enc2  enc3  enc4      var i   0       input   Base64  utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output   output           this  keyStr charAt enc1    this  keyStr charAt enc2            this  keyStr charAt enc3    this  keyStr charAt enc4               return output         public method for decoding decode   function  input        var output           var chr1  chr2  chr3      var enc1  enc2  enc3  enc4      var i   0       input   input replace    A-Za-z0-9        g            while  i  lt  input length             enc1   this  keyStr indexOf input charAt i              enc2   this  keyStr indexOf input charAt i              enc3   this  keyStr indexOf input charAt i              enc4   this  keyStr indexOf input charAt i               chr1    enc1  lt  lt  2     enc2  gt  gt  4           chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2           chr3     enc3  amp  3   lt  lt  6    enc4           output   output   String fromCharCode chr1            if  enc3    64                output   output   String fromCharCode chr2                     if  enc4    64                output   output   String fromCharCode chr3                         output   Base64  utf8 decode output        return output          private method for UTF-8 encoding  utf8 encode   function  string        string   string replace   r n g   n        var utftext            for  var n   0  n  lt  string length  n               var c   string charCodeAt n            if  c  lt  128                utftext    String fromCharCode c                     else if  c  gt  127   amp  amp   c  lt  2048                 utftext    String fromCharCode  c  gt  gt  6    192               utftext    String fromCharCode  c  amp  63    128                     else               utftext    String fromCharCode  c  gt  gt  12    224               utftext    String fromCharCode   c  gt  gt  6   amp  63    128               utftext    String fromCharCode  c  amp  63    128                         return utftext         private method for UTF-8 decoding  utf8 decode   function  utftext        var string           var i   0      var c   c1   c2   0       while   i  lt  utftext length              c   utftext charCodeAt i            if  c  lt  128                string    String fromCharCode c               i                      else if  c  gt  191   amp  amp   c  lt  224                 c2   utftext charCodeAt i 1               string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                i    2                    else               c2   utftext charCodeAt i 1               c3   utftext charCodeAt i 2               string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                i    3                        return string         Also  search on  javascript base64 encoding  turns a lot of other options  the above was the first one

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JS without btoa middlestep  no lib  In question title you write about string conversion  but in question you talk about binary data  picture  so here is function which make proper conversion starting from PNG picture binary data  details and reversal conversion here     x000D   x000D  function bytesArrToBase64 arr      const abc    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789        base64 alphabet   const bin   n   gt  n toString 2  padStart 8 0      convert num to 8-bit binary string   const l   arr length   let result          for let i 0  i lt   l-1  3  i          let c1   i 3 1 gt  l     case when     is on end     let c2   i 3 2 gt  l     case when     is on end     let chunk   bin arr 3 i     bin c1  0 arr 3 i 1     bin c2  0 arr 3 i 2        let r   chunk match    1 6  g  map  x j   gt  j  3 amp  amp c2         j  2 amp  amp c1       abc    0b  x            result    r join             return result          TEST  const pic        PNG binary data     0x89  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0x7d  0x08  0x8f      0x89  0x76  0x54  0xf1  0x1b  0x19  0x92  0xef  0x2c  0xbe  0x46  0x8e      0xa6  0x49  0x5e  0x61  0x89  0xe4  0x05  0x5e  0x4e  0xa4  0x5c  0x10      0x6e  0x9f  0xfc  0x5b  0x00  0x00  0x00  0x00  0x49  0x45  0x4e  0x44      0xae  0x42  0x60  0x82     let b64pic   bytesArrToBase64 pic   myPic src    data image png base64   b64pic  msg innerHTML    Base64 encoded pic data  lt br gt     b64pic  x000D  img   zoom  10  image-rendering  pixelated     msg   word-break  break-all    x000D   lt img id  myPic  gt   lt code id  msg  gt  lt  code gt  x000D   x000D   x000D

User · Answer

Here is an AngularJS Factory version of  user850789 s one    use strict    var ProjectNameBase64Factory   angular module  project name factories base64         ProjectNameBase64Factory factory  Base64   function          var Base64                private property          keyStr   ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789                  public method for encoding         encode  function  input                var output                   var chr1  chr2  chr3  enc1  enc2  enc3  enc4              var i   0               input   Base64  utf8 encode input                while  i  lt  input length                     chr1   input charCodeAt i                     chr2   input charCodeAt i                     chr3   input charCodeAt i                      enc1   chr1  gt  gt  2                  enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4                   enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6                   enc4   chr3  amp  63                   if  isNaN chr2                         enc3   enc4   64                    else if  isNaN chr3                         enc4   64                                     output   output                            Base64  keyStr charAt enc1    Base64  keyStr charAt enc2                             Base64  keyStr charAt enc3    Base64  keyStr charAt enc4                               return output                         public method for decoding         decode  function  input                var output                   var chr1  chr2  chr3              var enc1  enc2  enc3  enc4              var i   0               input   input replace    A-Za-z0-9        g                    while  i  lt  input length                     enc1   Base64  keyStr indexOf input charAt i                      enc2   Base64  keyStr indexOf input charAt i                      enc3   Base64  keyStr indexOf input charAt i                      enc4   Base64  keyStr indexOf input charAt i                       chr1    enc1  lt  lt  2     enc2  gt  gt  4                   chr2     enc2  amp  15   lt  lt  4     enc3  gt  gt  2                   chr3     enc3  amp  3   lt  lt  6    enc4                   output   output   String fromCharCode chr1                    if  enc3    64                        output   output   String fromCharCode chr2                                     if  enc4    64                        output   output   String fromCharCode chr3                                                 output   Base64  utf8 decode output                return output                          private method for UTF-8 encoding          utf8 encode  function  string                string   string replace   r n g    n                var utftext                    for  var n   0  n  lt  string length  n                       var c   string charCodeAt n                    if  c  lt  128                        utftext    String fromCharCode c                                     else if   c  gt  127   amp  amp   c  lt  2048                         utftext    String fromCharCode  c  gt  gt  6    192                       utftext    String fromCharCode  c  amp  63    128                                     else                       utftext    String fromCharCode  c  gt  gt  12    224                       utftext    String fromCharCode   c  gt  gt  6   amp  63    128                       utftext    String fromCharCode  c  amp  63    128                                                 return utftext                         private method for UTF-8 decoding          utf8 decode  function  utftext                var string                   var i   0              var c   0  c2   0  c3   0               while  i  lt  utftext length                     c   utftext charCodeAt i                    if  c  lt  128                        string    String fromCharCode c                       i                                      else if   c  gt  191   amp  amp   c  lt  224                         c2   utftext charCodeAt i   1                       string    String fromCharCode   c  amp  31   lt  lt  6     c2  amp  63                        i    2                                    else                       c2   utftext charCodeAt i   1                       c3   utftext charCodeAt i   2                       string    String fromCharCode   c  amp  15   lt  lt  12      c2  amp  63   lt  lt  6     c3  amp  63                        i    3                                               return string                       return Base64

User · Answer

You can use window btoa and window atob     const encoded   window btoa  Alireza Dezfoolian       encode a string const decoded   window atob encoded      decode the string   Probably using the way which MDN is can do your job the best    Also accepting unicode    using these two simple functions      ucs-2 string to base64 encoded ascii function utoa str        return window btoa unescape encodeURIComponent str          base64 encoded ascii to ucs-2 string function atou str        return decodeURIComponent escape window atob str          Usage  utoa       la mode       4pyTIMOgIGxhIG1vZGU  atou  4pyTIMOgIGxhIG1vZGU              la mode   utoa  I  u2661 Unicode        SSDimaEgVW5pY29kZSE  atou  SSDimaEgVW5pY29kZSE         I   Unicode

User · Answer

For my project I still need to support IE7 and work with large input to encode   Based on the code proposed by Joe Dyndale and as suggested in comment by Marius  it is possible to improve the performance with IE7 by constructing the result with an array instead of a string   Here is the example for encode   var encode   function  input        var output       chr1  chr2  chr3  enc1  enc2  enc3  enc4  i   0       input    utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output push  keyStr charAt enc1            output push  keyStr charAt enc2            output push  keyStr charAt enc3            output push  keyStr charAt enc4                return output join

User · Answer

Here is a LIVE DEMO of atob   and btoa   JS built in functions    lt  DOCTYPE html gt   lt html gt     lt head gt       lt style gt        textarea          width 30           height 100px               lt  style gt       lt script gt           encode string to base64       function encode                   var txt   document getElementById  txt1   value          var result   btoa txt           document getElementById  txt2   value   result                   decode base64 back to original string       function decode                   var txt   document getElementById  txt3   value          var result   atob txt           document getElementById  txt4   value   result               lt  script gt     lt  head gt     lt body gt       lt div gt         lt textarea id  txt1  gt Some text to decode        lt  textarea gt       lt  div gt       lt div gt         lt input type  button  id  btnencode  value  Encode  onClick  encode     gt       lt  div gt       lt div gt         lt textarea id  txt2  gt         lt  textarea gt       lt  div gt       lt br  gt       lt div gt         lt textarea id  txt3  gt U29tZSB0ZXh0IHRvIGRlY29kZQ          lt  textarea gt       lt  div gt       lt div gt         lt input type  button  id  btndecode  value  Decode  onClick  decode     gt       lt  div gt       lt div gt         lt textarea id  txt4  gt         lt  textarea gt       lt  div gt     lt  body gt   lt  html gt

User · Answer

While a bit more work  if you want a high performance native solution there are some HTML5 functions you can use   If you can get your data into a Blob  then you can use the FileReader readAsDataURL   function to get a data    URL and chop off the front of it to get at the base64 data   You may have to do further processing however to urldecode the data  as I m not sure whether   characters are escaped or not for the data    URL  but this should be pretty trivial

User · Answer

For my project I still need to support IE7 and work with large input to encode   Based on the code proposed by Joe Dyndale and as suggested in comment by Marius  it is possible to improve the performance with IE7 by constructing the result with an array instead of a string   Here is the example for encode   var encode   function  input        var output       chr1  chr2  chr3  enc1  enc2  enc3  enc4  i   0       input    utf8 encode input        while  i  lt  input length             chr1   input charCodeAt i             chr2   input charCodeAt i             chr3   input charCodeAt i              enc1   chr1  gt  gt  2          enc2     chr1  amp  3   lt  lt  4     chr2  gt  gt  4           enc3     chr2  amp  15   lt  lt  2     chr3  gt  gt  6           enc4   chr3  amp  63           if  isNaN chr2                 enc3   enc4   64            else if  isNaN chr3                 enc4   64                     output push  keyStr charAt enc1            output push  keyStr charAt enc2            output push  keyStr charAt enc3            output push  keyStr charAt enc4                return output join

User · Answer

For newer browsers to encode Uint8Array to string  and decode string to Uint8Array   const base64         decode  s   gt  Uint8Array from atob s   c   gt  c charCodeAt 0        encode  b   gt  btoa String fromCharCode    new Uint8Array b         For Node js you can use the following to encode string  Buffer  or Uint8Array to string  and decode from string  Buffer  or Uint8Array to Buffer   const base64         decode  s   gt  Buffer from s   base64        encode  b   gt  Buffer from b  toString  base64

[javascript] How can you encode a string to Base64 in JavaScript?

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