javascript - parse - unexpected token o in json at position 1




Safely turning a JSON string into an object (17)

Given a string of JSON data, how can you safely turn that string into a JavaScript object?

Obviously you can do this unsafely with something like...

var obj = eval("(" + json + ')');

...but that leaves us vulnerable to the json string containing other code, which it seems very dangerous to simply eval.


Summary:

Javascript (both browser and NodeJS) have a built in JSON object. On this Object are 2 convenient methods for dealing with JSON. They are the following:

  1. JSON.parse() Takes JSON as argument, returns JS object
  2. JSON.stringify() Takes JS object as argument returns JSON object

Other applications:

Besides for very conveniently dealing with JSON they have can be used for other means. The combination of both JSON methods allows us to make very easy make deep clones of arrays or objects. For example:

let arr1 = [1, 2, [3 ,4]];
let newArr = arr1.slice();

arr1[2][0] = 'changed'; 
console.log(newArr); // not a deep clone

let arr2 = [1, 2, [3 ,4]];
let newArrDeepclone = JSON.parse(JSON.stringify(arr2));

arr2[2][0] = 'changed'; 
console.log(newArrDeepclone); // A deep clone, values unchanged

JSON.parse(jsonString) is a pure JavaScript approach so long as you can guarantee a reasonably modern browser.


Officially documented:

The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.

Syntax

JSON.parse(text[, reviver])

Parameters

text

The string to parse as JSON. See the JSON object for a description of JSON syntax.

reviver (optional)

If a function, this prescribes how the value originally produced by parsing is transformed, before being returned.

Return value

The Object corresponding to the given JSON text.

Exceptions

Throws a SyntaxError exception if the string to parse is not valid JSON.


Converting the object to JSON, and then parsing it, works for me, like:

JSON.parse(JSON.stringify(object))

I have successfully been using json_sans_eval for a while now. According to its author, it is more secure than json2.js.


I'm not sure about other ways to do it but here's how you do it in Prototype (JSON tutorial).

new Ajax.Request('/some_url', {
  method:'get',
  requestHeaders: {Accept: 'application/json'},
  onSuccess: function(transport){
    var json = transport.responseText.evalJSON(true);
  }
});

Calling evalJSON() with true as the argument sanitizes the incoming string.


If your JavaScript are in Mootools the JSON.parse will be Anonymous by the Framework.
A valid syntax to safely turning a JSON string into an object shall be:

var object = JSON.decode(string[, secure]);

Moreover a JSON Request is can raise an object that able to parse directly.
You may cek how it turn a json raw data here:

http://jsfiddle.net/chetabahana/qbx9b5pm/


JSON parsing is always pain in ass. If the input is not as expected it throws an error and crashes what you are doing. You can use the following tiny function to safely parse your input. It always turns an object even if the input is not valid or is already an object which is better for most cases.

JSON.safeParse = function (input, def) {
  // Convert null to empty object
  if (!input) {
    return def || {};
  } else if (Object.prototype.toString.call(input) === '[object Object]') {
    return input;
  }
  try {
    return JSON.parse(input);
  } catch (e) {
    return def || {};
  }
};

Just for fun, here is the way using function :

 jsonObject = (new Function('return ' + jsonFormatData))()

Older question, I know, however nobody notice this solution by using new Function(), an anonymous function that returns the data.


Just an example:

 var oData = 'test1:"This is my object",test2:"This is my object"';

 if( typeof oData !== 'object' )
  try {
   oData = (new Function('return {'+oData+'};'))();
  }
  catch(e) { oData=false; }

 if( typeof oData !== 'object' )
  { alert( 'Error in code' ); }
 else {
        alert( oData.test1 );
        alert( oData.test2 );
      }

This is a little more safe because it executes inside a function and do not compile in your code directly. So if there is a function declaration inside it, it will not be bound to the default window object.

I use this to 'compile' configuration settings of DOM elements (for example the data attribute) simple and fast.


The easiest way using parse() method:

var response = '{"result":true,"count":1}';
var JsonObject= JSON.parse(response);

then you can get the values of the Json elements, for example:

var myResponseResult = JsonObject.result;
var myResponseCount = JsonObject.count;

Using jQuery as described in the documentation:

JSON.parse(jsonString);

The jQuery method is now deprecated. Use this method instead:

let jsonObject = JSON.parse(jsonString);

Original answer using deprecated jQuery functionality:

If you're using jQuery just use:

jQuery.parseJSON( jsonString );

It's exactly what you're looking for (see the jQuery documentation).


Try this.This one is written in typescript.

         export function safeJsonParse(str: string) {
               try {
                 return JSON.parse(str);
                   } catch (e) {
                 return str;
                 }
           }

Try using the method with this Data object. ex:Data='{result:true,count:1}'

try {
  eval('var obj=' + Data);
  console.log(obj.count);
}
catch(e) {
  console.log(e.message);
}

This method really helps in Nodejs when you are working with serial port programming


Using JSON.parse is probably the best way. Here's an example live demo

var jsonRes = '{ "students" : [' +
          '{ "firstName":"Michel" , "lastName":"John" ,"age":18},' +
          '{ "firstName":"Richard" , "lastName":"Joe","age":20 },' +
          '{ "firstName":"James" , "lastName":"Henry","age":15 } ]}';
var studentObject = JSON.parse(jsonRes);

You also can use reviver function to filter.

var data = JSON.parse(jsonString, function reviver(key, value) {
   //your code here to filter
});

for more information read JSON.parse


JSON.parse(jsonString);

json.parse will change into object.







json