How to escape a JSON string containing newline characters using JavaScript

Question

I have to form a JSON string in which a value is having new line character  This has to be escaped and then posted using AJAX call  Can any one suggest a way to escape the string with JavaScript  I am not using jQuery

User · Answer

I m afraid to say that answer given by Alex is rather incorrect  to put it mildly    Some characters Alex tries to escape are not required to be escaped at all  like  amp  and      b is not at all the backspace character but rather a word boundary match Characters required to be escaped are not handled    This function   escape   function  str           TODO  escape  x75 4HEXDIG    chars     return str        replace       g                replace       g                 replace       g                replace    b  g     b          replace    f  g     f          replace    n  g     n          replace    r  g     r          replace    t  g     t              appears to be a better approximation

User · Answer

When using any form of Ajax  detailed documentation for the format of responses received from the CGI server seems to be lacking on the Web  Some entries here point out that newlines in returned text or json data must be escaped to prevent infinite loops  hangs  in JSON conversion  possibly created by throwing an uncaught exception   whether done automatically by jQuery or manually using Javascript system or library JSON parsing calls   In each case where programmers post this problem  inadequate solutions are presented  most often replacing  n by   n on the sending side  and the matter is dropped  Their inadequacy is revealed when passing string values that accidentally embed control escape sequences  such as Windows pathnames  An example is  C  Chris Roberts php   which contains the control characters  c and  r  which can cause JSON conversion of the string   file   C  Chris Roberts php   to loop forever  One way of generating such values is deliberately to attempt to pass PHP warning and error messages from server to client  a reasonable idea   By definition  Ajax uses HTTP connections behind the scenes  Such connections pass data using GET and POST  both of which require encoding sent data to avoid incorrect syntax  including control characters   This gives enough of a hint to construct what seems to be a solution  it needs more testing   to use rawurlencode on the PHP  sending  side to encode the data  and unescape on the Javascript  receiving  side to decode the data  In some cases  you will apply these to entire text strings  in other cases you will apply them only to values inside JSON   If this idea turns out to be correct  simple examples can be constructed to help programmers at all levels solve this problem once and for all

User · Answer

This is an old question but the solution did not work well for me as it did not solve all cases  I finally found an answer that did the job here  I will post my combined solution of both using escape and encode uri component      implement JSON stringify serialization JSON stringify   JSON stringify    function  obj        var t   typeof  obj       if  t     object     obj     null               simple data type         if  t     string   obj       obj              return String obj             else              recurse array or object         var n  v  json       arr    obj  amp  amp  obj constructor    Array           for  n in obj                v   obj n   t   typeof v               if  t     string   v       v                  else if  t     object   amp  amp  v     null  v   JSON stringify v               json push  arr              n           String v                      var rawString    arr                String json     arr                      return rawString           function escape  key  val        if  typeof val    string   return val       var replaced   encodeURIComponent val       return replaced     JSON stringifyEscaped   function obj       return JSON stringify obj escape

User · Answer

Like you  I have been looking into several comments and post to replace special escape characters in my JSON which contains html object inside that    My object is to remove the special characters in JSON object and also render the html which is inside the json object   Here is what I did and hope its very simple to use   First I did JSON stringify my json object and JSON parse the result   For eg   JSON parse JSON stringify jsonObject      And it solves my problem and done using Pure Javascript

User · Answer

Use json encode   if your server side scripting lang is PHP   json encode   escapes the newline  amp  other unexpected tokens for you  if not using PHP look for similar function for your scripting language   then use   parseJSON   in your JavaScript  done

User · Answer

I got same situation in one of my Ajax calls  where JSON was throwing an error due to the newline in the Textarea field  The solution given here didn t worked for me  So i used Javascript s  escape function and it worked fine  Then to retrieve the value from JSON  I just unescaped using  unescape

User · Answer

There is also second parameter on JSON stringify  So  more elegant solution would be   function escape  key  val        if  typeof val    string   return val      return val        replace       g                replace       g                 replace       g                replace    b  g     b          replace    f  g     f          replace    n  g     n          replace    r  g     r          replace    t  g     t             var myJSONString   JSON stringify myJSON escape

User · Answer

this is an old post  but it may still be helpful for those using angular fromJson  and JSON stringify  escape   is deprecated  use this instead   var uri enc   encodeURIComponent uri     before you post the contents var uri dec   decodeURIComponent uri enc     before you display use the contents    ref http   www w3schools com jsref jsref decodeuricomponent asp

User · Answer

Looks like this is an ancient post really  -  But guys  the best workaround I have for this  to be 100  that it works without complicated code  is to use both functions of encoding decoding to base64  These are atob   and btoa    By far the easiest and best way  no need to worry if you missed any characters to be escaped   George

User · Answer

A small update for single quotes  function escape  key  val        if  typeof val    string   return val      return val                replace       g                   replace       g                  replace    b  g     b            replace    f  g     f            replace    n  g     n            replace    r  g     r            replace    t  g     t            replace       g                  replace      g              var myJSONString   JSON stringify myJSON escape

User · Answer

It s better to use JSON parse yourUnescapedJson

User · Answer

I used the built in jQuery serialize   to extract the value from a textarea to urlencode the input  The pro part is that you don t have to search replace every special char on your own and i also keep the newlines and escapes html  For serialize to work it seems the input field needs to have a name attribute though and it also adds same attribute to the escaped string which needs to be replaced away  Might not be what you are looking for but it works for me   var myinputfield   jQuery   myinputfield     var text   myinputfield serialize    text   text replace myinputfield attr  name

User · Answer

Use encodeURIComponent   to encode the string   Eg  var myEscapedJSONString   encodeURIComponent JSON stringify myJSON     You don t need to decode it since the web server automatically do the same

User · Answer

Take your JSON and  stringify   it  Then use the  replace   method and replace all occurrences of  n with   n    EDIT   As far as I know of  there are no well-known JS libraries for escaping all special characters in a string  But  you could chain the  replace   method and replace all of the special characters like this   var myJSONString   JSON stringify myJSON   var myEscapedJSONString   myJSONString replace    n g     n                                          replace      g                                                replace      g                                                replace     amp  g      amp                                           replace    r g     r                                          replace    t g     t                                          replace    b g     b                                          replace    f g     f       myEscapedJSONString is now ready to be POST ed to the server     But that s pretty nasty  isn t it  Enter the beauty of functions  in that they allow you to break code into pieces and keep the main flow of your script clean  and free of 8 chained  replace   calls  So let s put that functionality into a function called  escapeSpecialChars    Let s go ahead and attach it to the prototype chain of the String object  so we can call escapeSpecialChars   directly on String objects   Like so   String prototype escapeSpecialChars   function         return this replace    n g     n                   replace      g                         replace      g                         replace     amp  g      amp                    replace    r g     r                   replace    t g     t                   replace    b g     b                   replace    f g     f         Once we have defined that function  the main body of our code is as simple as this   var myJSONString   JSON stringify myJSON   var myEscapedJSONString   myJSONString escapeSpecialChars       myEscapedJSONString is now ready to be POST ed to the server

User · Answer

As per user667073 suggested  except reordering the backslash replacement first  and fixing the quote replacement  escape   function  str      return str      replace       g               replace       g               replace       g              replace    b  g     b        replace    f  g     f        replace    n  g     n        replace    r  g     r        replace    t  g     t

User · Answer

EDIT  Check if the api you   re interacting with is set to Content-Type  application json   amp  or if your client http library is both stringify-ing and parsing the http request body behind the scenes  My client library was generated by swagger  and was the reason I needed to apply these hacks  as the client library was stringifying my pre-stringified body  body     jsonString     instead of body       normal payload     All I had to do was change the api to Content-Type  text plain  which removed the JSON stringify parsing on that route  and then none of these hacks were needed  You can also change only the  quot consumes quot  or  quot produces quot  portion of the api  see here  ORIGINAL  If your Googles keep landing you here and your api throws errors unless your JSON double quotes are escaped   quot    quot foo  quot   true  quot    all you need to do is stringify twice e g  JSON stringify JSON stringify bar

[javascript] How to escape a JSON string containing newline characters using JavaScript?

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