How can I check if a value is a json object

Question

My server side code returns a value which is a json object on success and a string  false  on failure  Now how can I check whether the returned value is a json object

User · Answer

i tried all of the suggested answers  nothing worked for me  so i had to use  jQuery isEmptyObject     hoe that helps someone else out with this issue

User · Answer

Since it s just false and json object  why don t you check whether it s false  otherwise it must be json   if ret    false    ret     false            json

User · Answer

I don t really like the accepted answer  First and foremost it requires jQuery  which is not always available or required  Secondly  it does a full stringification of the object which to me is overkill  Here s a simple function that thoroughly detects whether a value is JSON-like  using nothing more than a few parts of the lodash library for genericity     import   as isNull from  lodash isNull  import   as isPlainObject from  lodash isPlainObject  import   as isNumber from  lodash isNumber  import   as isBoolean from  lodash isBoolean  import   as isString from  lodash isString  import   as isArray from  lodash isArray   function isJSON val      if  isNull val        isBoolean val        isString val       return true    if  isNumber val         return  isNaN val   amp  amp  isFinite val    if  isArray val       return Array prototype every call val  isJSON    if  isPlainObject val         for  const key of Object keys val           if   isJSON val key            return false           return true       return false     I ve even taken the time to put it up in npm as a package  https   npmjs com package is-json-object  Use it together with something like Webpack to get it in the browser   Hope this helps someone

User · Answer

jQuery parseJSON   should return an object of type  object   if the string was JSON  so you only have to check the type with typeof  var response jQuery parseJSON  response from server    if typeof response    object          It is JSON   else     if response    false              the response was a string  false   parseJSON will convert it to boolean false       else            the response was something else

User · Answer

If you have jQuery  use isPlainObject   if    isPlainObject my var

User · Answer

You should return json always  but change its status  or in following example the ResponseCode property   if callbackResults ResponseCode   200           Some error  you can add a message too      else          All fine  proceed with code

User · Answer

var checkJSON   function m        if  typeof m     object            try  m   JSON stringify m           catch err    return false          if  typeof m     string           try  m   JSON parse m           catch  err    return false          if  typeof m     object     return false       return true        checkJSON JSON parse                true checkJSON JSON parse    a  0        true checkJSON                           true checkJSON    a  0                   true checkJSON  x                        false checkJSON                           false checkJSON                           false

User · Answer

var data    json string     var jdata   null  try       jdata     parseJSON data      catch e      if jdata      use jdata  else     use data

User · Answer

I am using this to validate JSON Object  function isJsonObject obj        try           JSON parse JSON stringify obj          catch  e            return false            return true      I am using this to validate JSON String  function isJsonString str        try           JSON parse str         catch  e            return false            return true

User · Answer

If you want to test explicitly for valid JSON  as opposed to the absence of the returned value false   then you can use a parsing approach as described here

User · Answer

Solution 3  fastest way           param Object     returns boolean     function isJSON  something        if  typeof something     string           something   JSON stringify something        try           JSON parse something           return true        catch  e            return false            You can use it   var myJson      user   chofoteddy      user   bart     isJSON myJson      true     The best way to validate that an object is of type JSON or array is as follows   var a           o         Solution 1  toString call o        object Object       true toString call a        object Array       true   Solution 2  a constructor name      Array      true o constructor name      Object      true   But  strictly speaking  an array is part of a JSON syntax  Therefore  the following two examples are part of a JSON response   console log response        message    success   console log response        user    bart    id  3    And   console log response         user   chofoteddy      user   bart    console log response        chofoteddy    bart       AJAX   JQuery  recommended   If you use JQuery to bring information via AJAX  I recommend you put in the  dataType  attribute the  json  value  that way if you get a JSON or not  JQuery validate it for you and make it known through their functions  success  and  error   Example     ajax       url   http   www something com       data      formId   serialize        method   POST       dataType   json           sucess  will be executed only if the response status is 200 and get a JSON     success  function  json              error  will run but receive state 200  but if you miss the JSON syntax     error  function  xhr

User · Answer

I know this thread has been answered already  but coming here didn t really solve my problems  I found this function somewhere else  maybe someone coming here will find it to be of some use to them   function getClass obj      if  typeof obj      undefined       return  undefined     if  obj     null      return  null     return Object prototype toString call obj       match     object s          1

User · Answer

The chosen solution doesn t actually work for me because I get a         Unexpected Token  lt      error in Chrome  This is because the error is thrown as soon as the parse comes across and unknown character  However  there is a way around this if you are returning only string values through ajax  which can be fairly useful if you are using PHP or ASPX to process ajax requests and might or might not return JSON depending on conditions   The solution is quite simple  you can do the following to check if it was a valid JSON return         var IS JSON   true         try                         var json     parseJSON msg                   catch err                          IS JSON   false                             As I have said before  this is the solution for if you are either returning string type stuff from your AJAX request or if you are returning mixed type

[jquery] How can I check if a value is a json object?

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