JSON.parse() not working

Question

I have a json from my server which is -

{"canApprove": true,"hasDisplayed": false}  

I can parse the json like this -

var msg = JSON.parse('{"canApprove": true,"hasDisplayed": false}');
alert(msg.canApprove);  //shows true.

At my ajax response function I caught the same json mentioned earlier by a method parameter jsonObject -

//response function
function(jsonObject){

  //here jsonObject contains the same json -  {"canApprove":true,"hasDisplayed": false}
  //But without the surrounding single quote
  //I have confirmed about this by seeing my server side log.

  var msg = JSON.parse(jsonObject); // this gives the error

}

But now I got the following error -

SyntaxError: JSON.parse: unexpected character at line 1 column 2 of the JSON data

Can anyone tell me why I am getting the error?

Answer 1

Your JsonObject seems is a Json Object. The reasons why you can't parse Json from a String:

• the String is surround by " ". and use \" escape inside example:

  "{\"name\":\"alan\",\"age\":34}"

  when you try to parse above string by JSON.parse(), still return the a string:{"name":"alan","age":34}, and \" is replace by ". But use the JSON.parse() again, it will return the object you want. So in this case,you can do this:

  JSON.parse(JSON.parse("{\"name\":\"alan\",\"age\":34}" ))

• use ' instead of " . example:

  {'name':'alan','age':34}

  when you try to parse above string by JSON.parse(), may cause error

Answer 2

I dont think you should call JSON.parse(jsonObject) if the server is sending valid JSON as it will be parsed automatically when it retrieves the response. I believe that if You set the Content-type: application/json header it will be parsed automatically.

Try using jsonObject as if it was already parsed, something like:

console.log(jsonObject.canApprove);

Without calling JSON.parse before.