Example JavaScript code to parse CSV data

Question

Where could I find some JavaScript code to parse CSV data

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Here s my simple vanilla JavaScript code  let a    one two  quot three  but with a comma quot  four  quot five  with  quot  quot quotes quot  quot  in it   quot   console log splitQuotes a    function splitQuotes line      if line indexOf   quot     lt  0       return line split         let result       cell       quote   false    for let i   0  i  lt  line length  i          char   line i      if char      quot    amp  amp  line i 1       quot            cell    char       i         else if char      quot            quote    quote        else if  quote  amp  amp  char                 result push cell        cell            else         cell    char           if   i    line length-1  amp  amp  cell          result push cell              return result

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You can use the CSVToArray   function mentioned in this blog entry    lt script type  text javascript  gt         ref  http   stackoverflow com a 1293163 2343        This will parse a delimited string into an array of        arrays  The default delimiter is the comma  but this        can be overriden in the second argument      function CSVToArray  strData  strDelimiter               Check to see if the delimiter is defined  If not             then default to comma          strDelimiter    strDelimiter                      Create a regular expression to parse the CSV values          var objPattern   new RegExp                                   Delimiters                          strDelimiter       r   n   r                           Quoted fields                                                                          Standard fields                              strDelimiter      r  n                                  gi                              Create an array to hold our data  Give the array            a default empty first row          var arrData                     Create an array to hold our individual pattern            matching groups          var arrMatches   null               Keep looping over the regular expression matches            until we can no longer find a match          while  arrMatches   objPattern exec  strData                     Get the delimiter that was found              var strMatchedDelimiter   arrMatches  1                    Check to see if the given delimiter has a length                 is not the start of string  and if it matches                field delimiter  If id does not  then we know                that this delimiter is a row delimiter              if                   strMatchedDelimiter length  amp  amp                  strMatchedDelimiter     strDelimiter                                        Since we have reached a new row of data                     add an empty row to our data array                  arrData push                                    var strMatchedValue                  Now that we have our delimiter out of the way                 let s check to see which kind of value we                captured  quoted or unquoted               if  arrMatches  2                         We found a quoted value  When we capture                    this value  unescape any double quotes                  strMatchedValue   arrMatches  2   replace                      new RegExp           g                                                                    else                       We found a non-quoted value                  strMatchedValue   arrMatches  3                                    Now that we have our value string  let s add                it to the data array              arrData  arrData length - 1   push  strMatchedValue                          Return the parsed data          return  arrData            lt  script gt

User · Answer

Just use  split       var str    quot How are you doing today  quot   var n   str split  quot   quot

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Here s my PEG  js  grammar that seems to do ok at RFC 4180  i e  it handles the examples at http   en wikipedia org wiki Comma-separated values    start       n r   first line rest    n r   data line   return data        n r     rest unshift first   return rest     line     first field rest      text field   return text           amp    return   first    rest length       ignore blank lines       rest unshift first   return rest     field         text char        return text join            text    n r      return text join         char               return                   Try it out at http   jsfiddle net knvzk 10 or http   pegjs majda cz online  Download the generated parser at https   gist github com 3362830

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jQuery-CSV It s a jQuery plugin designed to work as an end-to-end solution for parsing CSV into JavaScript data  It handles every single edge case presented in RFC 4180  as well as some that pop up for Excel Google spreadsheet exports  i e   mostly involving null values  that the specification is missing  Example   track artist album year Dangerous  Busta Rhymes   When Disaster Strikes  1997     Calling this music     csv toArrays csv      Outputs          quot track quot    quot artist quot    quot album quot    quot year quot        quot Dangerous quot    quot Busta Rhymes quot    quot When Disaster Strikes quot    quot 1997 quot      console log music 1  2      Outputs   When Disaster Strikes   Update  Oh yeah  I should also probably mention that it s completely configurable  music     csv toArrays csv      delimiter   quot   quot      Sets a custom value delimiter character   separator          Sets a custom field separator character      Update 2  It now works with jQuery on Node js too  So you have the option of doing either client-side or server-side parsing with the same library  Update 3  Since the Google Code shutdown  jquery-csv has been migrated to GitHub  Disclaimer  I am also the author of jQuery-CSV

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I m not sure why I couldn t get Kirtan s example to work for me  It seemed to be failing on empty fields or maybe fields with trailing commas    This one seems to handle both  I did not write the parser code  just a wrapper around the parser function to make this work for a file  See attribution      var Strings                            Wrapped CSV line parser             param s      String delimited CSV string             param sep    Separator override             attribution  http   www greywyvern com  post 258  comments closed on blog                          parseCSV   function s sep                   http   stackoverflow com questions 1155678 javascript-string-newline-character             var universalNewline     r n  r  n g              var a   s split universalNewline               for var i in a                   for  var f   a i  split sep   sep     quot   quot    x   f length - 1  tl  x  gt   0  x--                        if  f x  replace   quot  s       quot    charAt f x  length - 1       quot                              if   tl   f x  replace    s  quot      quot     length  gt  1  amp  amp  tl charAt 0       quot                                  f x    f x  replace    s  quot   quot  s   g      replace   quot  quot  g    quot                                 else if  x                            f splice x - 1  2   f x - 1   f x   join sep                            else f   f shift   split sep  concat f                         else f x  replace   quot  quot  g    quot                         a i    f                    return a

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Here s an extremely simple CSV parser that handles quoted fields with commas  new lines  and escaped double quotation marks  There s no splitting or regular expression  It scans the input string 1-2 characters at a time and builds an array  Test it at http   jsfiddle net vHKYH   function parseCSV str        var arr           var quote   false       true  means we re inside a quoted field         Iterate over each character  keep track of current row and column  of the returned array      for  var row   0  col   0  c   0  c  lt  str length  c              var cc   str c   nc   str c 1             Current character  next character         arr row    arr row                        Create a new row if necessary         arr row  col    arr row  col              Create a new column  start with empty string  if necessary             If the current character is a quotation mark  and we re inside a            quoted field  and the next character is also a quotation mark             add a quotation mark to the current column and skip the next character         if  cc      quot    amp  amp  quote  amp  amp  nc      quot      arr row  col     cc    c  continue                If it s just one quotation mark  begin end quoted field         if  cc      quot      quote    quote  continue                If it s a comma and we re not in a quoted field  move on to the next column         if  cc         amp  amp   quote      col  continue                If it s a newline  CRLF  and we re not in a quoted field  skip the next character            and move on to the next row and move to column 0 of that new row         if  cc      r   amp  amp  nc      n   amp  amp   quote      row  col   0    c  continue                If it s a newline  LF or CR  and we re not in a quoted field             move on to the next row and move to column 0 of that new row         if  cc      n   amp  amp   quote      row  col   0  continue            if  cc      r   amp  amp   quote      row  col   0  continue                Otherwise  append the current character to the current column         arr row  col     cc            return arr

User · Answer

Regular expressions to the rescue  These few lines of code handle properly quoted fields with embedded commas  quotes  and newlines based on the RFC 4180 standard   function parseCsv data  fieldSep  newLine        fieldSep   fieldSep             newLine   newLine      n       var nSep     x1D       var qSep     x1E       var cSep     x1F       var nSepRe   new RegExp nSep   g        var qSepRe   new RegExp qSep   g        var cSepRe   new RegExp cSep   g        var fieldRe   new RegExp     lt          fieldSep      n         s  S      lt                     fieldSep      n       g        var grid           data replace   r g      replace   n         replace fieldRe  function match  p1  p2            return p2 replace   n g  nSep  replace     g  qSep  replace    g  cSep          split   n   forEach function line            var row   line split fieldSep  map function cell                return cell replace nSepRe  newLine  replace qSepRe       replace cSepRe                            grid push row               return grid     const csv    A1 B1 C1 n A   2     B  2   C n2    const separator                field separator  default      const newline      lt br   gt        newline representation in case a field contains newlines  default    n   var grid   parseCsv csv  separator  newline      expected       A1    B1    C1        A  2     B  2    C  lt br   gt  2        You don t need a parser-generator such as lex yacc  The regular expression handles RFC 4180 properly thanks to positive lookbehind  negative lookbehind  and positive lookahead   Clone download code at https   github com peterthoeny parse-csv-js

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I have an implementation as part of a spreadsheet project  This code is not yet tested thoroughly  but anyone is welcome to use it  As some of the answers noted though  your implementation can be much simpler if you actually have DSV or TSV file  as they disallow the use of the record and field separators in the values  CSV  on the other hand  can actually have commas and newlines inside a field  which breaks most regular expression and split-based approaches  var CSV         parse  function csv  reviver            reviver   reviver    function r  c  v    return v             var chars   csv split      c   0  cc   chars length  start  end  table       row          while  c  lt  cc                table push row                    while  c  lt  cc  amp  amp    r      chars c   amp  amp    n      chars c                     start   end   c                  if    quot       chars c                        start   end     c                      while  c  lt  cc                            if    quot       chars c                                 if    quot       chars c 1                                     break                                                            else                                   chars   c           unescape  quot  quot                                                                                  end     c                                            if    quot       chars c                               c                                            while  c  lt  cc  amp  amp    r      chars c   amp  amp    n      chars c   amp  amp          chars c                               c                                          else                       while  c  lt  cc  amp  amp    r      chars c   amp  amp    n      chars c   amp  amp          chars c                             end     c                                                          row push reviver table length-1  row length  chars slice start  end  join                        if          chars c                           c                                              if    r      chars c                       c                            if    n      chars c                       c                                  return table              stringify  function table  replacer            replacer   replacer    function r  c  v    return v             var csv       c  cc  r  rr   table length  cell          for  r   0  r  lt  rr    r                if  r                    csv      r n                             for  c   0  cc   table r  length  c  lt  cc    c                    if  c                        csv                                           cell   replacer r  c  table r  c                    if      r n quot    test cell                         cell     quot     cell replace   quot  g    quot  quot        quot                                      csv     cell    0     cell    cell                                       return csv

User · Answer

csvToArray v1 3 A compact  645 bytes   but compliant function to convert a CSV string into a 2D array  conforming to the RFC4180 standard  https   code google com archive p csv-to-array downloads Common Usage  jQuery    ajax           url   quot test csv quot           dataType   text           cache  false     done function csvAsString           csvAsArray csvAsString csvToArray          Common usage  JavaScript csvAsArray   csvAsString csvToArray     Override field separator csvAsArray   csvAsString csvToArray  quot   quot     Override record separator csvAsArray   csvAsString csvToArray  quot  quot    quot   quot     Override Skip Header csvAsArray   csvAsString csvToArray  quot  quot    quot  quot   1    Override all csvAsArray   csvAsString csvToArray  quot   quot    quot   quot   1

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Here s another solution  This uses   a coarse global regular expression for splitting the CSV string  which includes surrounding quotes and trailing commas  fine-grained regular expression for cleaning up the surrounding quotes and trailing commas also  has type correction differentiating strings  numbers and boolean values  For the following input string   quot This is   a value quot  Hello 4 -123 3 1415  This is also   possible  true  The code outputs       quot This is  a value quot      quot Hello quot     4    -123    3 1415     quot This is also  possible quot     true    Here s my implementation of parseCSVLine   in a runnable code snippet   x000D   x000D  function parseCSVLine text      return text match    s                       s       g   map  function  text        let m      if  m   text match    s           s        return m 1      Double Quoted Text     if  m   text match    s         s        return m 1      Single Quoted Text     if  m   text match    s  true false  s        return m 1       true      Boolean     if  m   text match    s         -   d   s        return parseInt m 1       Integer Number     if  m   text match    s         -   d    d   s        return parseFloat m 1       Floating Number     if  m   text match    s       s        return m 1      Unquoted Text     return text            let data     This is   a value  Hello 4 -123 3 1415  This is also   possible  true   let obj   parseCSVLine data   console log  JSON stringify  obj  undefined  2      x000D   x000D   x000D

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I have constructed this JavaScript script to parse a CSV in string to array object  I find it better to break down the whole CSV into lines  fields and process them accordingly  I think that it will make it easy for you to change the code to suit your need                       CSV to object                    const new line char     n       const field separator char             function parse csv csv str             var result                let line end index moved   false          let line start index   0          let line end index   0          let csr index   0          let cursor val   csv str csr index           let found new line char   get new line char csv str           let in quote   false              Handle  r n         if  found new line char      r n                 csv str   csv str split found new line char  join new line char                        Handle the last character is not  n         if  csv str csv str length - 1      new line char                csv str    new line char                     while  csr index  lt  csv str length                if  cursor val       quot                      in quote    in quote                else if  cursor val     new line char                    if  in quote     false                        if  line end index moved  amp  amp   line start index  lt   line end index                             result push parse csv line csv str substring line start index  line end index                             line start index   csr index   1                           Else  just ignore line end index has not moved or line has not been sliced for parsing the line                      Else  just ignore because we are in a quote                           csr index                cursor val   csv str csr index               line end index   csr index              line end index moved   true                        Handle  r n         if  found new line char      r n                 let new result                   let curr row              for  var i   0  i  lt  result length  i                      curr row                       for  var j   0  j  lt  result i  length  j                          curr row push result i  j  split new line char  join   r n                                       new result push curr row                             result   new result                    return result             function parse csv line csv line str             var result                  let field end index moved   false          let field start index   0          let field end index   0          let csr index   0          let cursor val   csv line str csr index           let in quote   false              Pretend that the last char is the separator char to complete the loop         csv line str    field separator char           while  csr index  lt  csv line str length                if  cursor val       quot                      in quote    in quote                else if  cursor val     field separator char                    if  in quote     false                        if  field start index  lt   field end index                            result push parse csv field csv line str substring field start index  field end index                             field start index   csr index   1                           Else  just ignore field end index has not moved or field has not been sliced for parsing the field                      Else  just ignore because we are in quote                           csr index                cursor val   csv line str csr index               field end index   csr index              field end index moved   true                    return result             function parse csv field csv field str            with quote    csv field str 0        quot              if  with quote                csv field str   csv field str substring 1  csv field str length - 1      remove the start and end quotes             csv field str   csv field str split   quot  quot    join   quot        handle double quotes                   return csv field str                Initial method  check the first newline character only     function get new line char csv str            if  csv str indexOf   r n    gt  -1                return   r n             else               return   n

[javascript] Example JavaScript code to parse CSV data

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