jQuery parseJSON throws Invalid JSON error due to escaped single quote in JSON

Question

I   m making requests to my server using jQuery post   and my server is returning JSON objects  like    var    value           However  if any of the values contains a single quote  properly escaped like      jQuery fails to parse an otherwise valid JSON string  Here   s an example of what I mean  done in Chrome   s console    data        status      success      newHtml      Hello     x       eval  x       data        newHtml   Hello  x   status   success       parseJSON data      Invalid JSON     status    success    newHtml    Hello   x      Is this normal  Is there no way to properly pass a single quote via JSON

User · Answer

Striking a similar issue using CakePHP to output a JavaScript script-block using PHP's native json_encode. $contractorCompanies contains values that have single quotation marks and as explained above and expected json_encode($contractorCompanies) doesn't escape them because its valid JSON.

<?php $this->Html->scriptBlock("var contractorCompanies = jQuery.parseJSON( '".(json_encode($contractorCompanies)."' );"); ?>

By adding addslashes() around the JSON encoded string you then escape the quotation marks allowing Cake / PHP to echo the correct javascript to the browser. JS errors disappear.

<?php $this->Html->scriptBlock("var contractorCompanies = jQuery.parseJSON( '".addslashes(json_encode($contractorCompanies))."' );"); ?>

User · Answer

According to the state machine diagram on the JSON website  only escaped double-quote characters are allowed  not single-quotes  Single quote characters do not need to be escaped      Update - More information for those that are interested     Douglas Crockford does not specifically say why the JSON specification does not allow escaped single quotes within strings  However  during his discussion of JSON in Appendix E of JavaScript  The Good Parts  he writes      JSON s design goals were to be minimal  portable  textual  and a subset of JavaScript  The less we need to agree on in order to interoperate  the more easily we can interoperate    So perhaps he decided to only allow strings to be defined using double-quotes since this is one less rule that all JSON implementations must agree on  As a result  it is impossible for a single quote character within a string to accidentally terminate the string  because by definition a string can only be terminated by a double-quote character  Hence there is no need to allow escaping of a single quote character in the formal specification    Digging a little bit deeper  Crockford s org json implementation of JSON for Java is more permissible and does allow single quote characters      The texts produced by the toString methods strictly conform to the JSON syntax rules  The constructors are more forgiving in the texts they will accept                   Strings may be quoted with    single quote        This is confirmed by the JSONTokener source code  The nextString method accepts escaped single quote characters and treats them just like double-quote characters   public String nextString char quote  throws JSONException       char c      StringBuffer sb   new StringBuffer        for                c   next            switch  c                          case                   c   this next                switch  c                                  case                  case                   case                   case                      sb append c                   break                At the top of the method is an informative comment      The formal JSON format does not allow strings in single quotes  but an implementation is allowed to accept them    So some implementations will accept single quotes - but you should not rely on this  Many popular implementations are quite restrictive in this regard and will reject JSON that contains single quoted strings and or escaped single quotes     Finally to tie this back to the original question  jQuery parseJSON first attempts to use the browser s native JSON parser or a loaded library such as json2 js where applicable  which on a side note is the library the jQuery logic is based on if JSON is not defined   Thus jQuery can only be as permissive as that underlying implementation   parseJSON  function  data                     Attempt to parse using the native JSON parser first     if   window JSON  amp  amp  window JSON parse             return window JSON parse  data                        jQuery error   Invalid JSON      data         As far as I know these implementations only adhere to the official JSON specification and do not accept single quotes  hence neither does jQuery

User · Answer

I understand where the problem lies and when I look at the specs its clear that unescaped single quotes should be parsed correctly   I am using jquery s jQuery parseJSON function to parse the JSON string but still getting the parse error when there is a single quote in the data that is prepared with json encode   Could it be a mistake in my implementation that looks like this  PHP - server side     data   array      elem   array     elem  name      Erik    elem  position      PHP Programmer    data     json encode  elem     elem   array     elem  name      Carl    elem  position      C Programmer    data     json encode  elem     jsonString         implode        data           The final step is that I store the JSON encoded string into an JS variable    lt script type  text javascript  gt  employees   jQuery parseJSON   lt    marker    gt      lt  script gt    If I use    instead of    it still throws an error   SOLUTION   The only thing that worked for me was to use bitmask JSON HEX APOS to convert the single quotes like this   json encode  tmp  JSON HEX APOS     Is there another way of tackle this issue  Is my code wrong or poorly written   Thanks

User · Answer

When You are sending a single quote in a query  empid     T via  empid  escape empid    When You get the value including a single quote  var xxx    request QueryString  empid   xxx  unscape xxx    If you want to search  insert the value which includes a single quote in a query xxx Replace empid

User · Answer

If you need a single quote inside of a string  since    is undefined by the spec  use  u0027   see http   www utf8-chartable de  for all of them  edit  please excuse my misuse of the word backticks in the comments   I meant backslash   My point here is that in the event you have nested strings inside other strings  I think it can be more useful and readable to use unicode instead of lots of backslashes to escape a single quote   If you are not nested however it truly is easier to just put a plain old quote in there

User · Answer

I was trying to save a JSON object from a XHR request into a HTML5 data-  attribute  I tried many of above solutions with no success   What I finally end up doing was replacing the single quote   with it code  amp  39  using a regex after the stringify   method call the following way    var productToString   JSON stringify productObject   var quoteReplaced   productToString replace    g    amp  39     var anchor     lt a data-product       quoteReplaced       href       gt     productObject name     lt  a gt       Here you can use the  anchor  variable to update your DOM element

User · Answer

Interesting  How are you generating your JSON on the server end  Are you using a library function  such as json encode in PHP   or are you building the JSON string by hand   The only thing that grabs my attention is the escape apostrophe       Seeing as you re using double quotes  as you indeed should  there is no need to escape single quotes  I can t check if that is indeed the cause for your jQuery error  as I haven t updated to version 1 4 1 myself yet

[javascript] jQuery.parseJSON throws “Invalid JSON” error due to escaped single quote in JSON

Examples related to javascript

Examples related to jquery

Examples related to json