Serializing an object to JSON

Question

How can I serialize an object to JSON in JavaScript?

score 298 · Accepted Answer · edited Jan 15 '23 at 19:52

298

You’re looking for JSON.stringify.

Examples:

const object = {
    hello: "world",
    "some array": [ 42, 69, 420, 1337, null, true ]
  },
  primitive = false;

console.log(JSON.stringify(object)); // "{\"hello\":\"world\",\"some array\":[42,69,420,1337,null,true]}"
console.log(JSON.stringify(primitive)); // "false"

edited Jan 15 '23 at 19:52

Sebastian Simon

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answered Feb 17 '09 at 20:16

Mike_G

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Using JSON.stringify() with javascript objects containing arrays have a little thing to it. Please check my question: http://stackoverflow.com/questions/25423883/parsing-json-array-gives-error – uylmz Aug 21 '14 at 12:33
@uylmz I don’t think this bug exists anymore in 2023. – Sebastian Simon Jan 15 '23 at 12:44

score 52 · Answer 2 · edited May 12 '15 at 11:00

52

Download https://github.com/douglascrockford/JSON-js/blob/master/json2.js, include it and do

var json_data = JSON.stringify(obj);

edited May 12 '15 at 11:00

bartektartanus

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answered Feb 17 '09 at 20:18

Johannes Weiss

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Should I really need to include "json2.js"? It seems to works without it. – Pavel Alexeev Mar 31 '12 at 08:28
33

@PavelAlexeev No, you don't neet to include `json2.js` anymore, unless you are targetting very old browsers: modern browsers include a native implementation of the `JSON` object. The good thing about `json2.js` is that it will only kick in if no native object is found. See [http://stackoverflow.com/questions/891299/browser-native-json-support-window-json] for a detailed breakdown of browser support. – Edurne Pascual May 10 '12 at 08:14

AvL · Answer 3 · 2023-01-19T12:19:13.190

4

Just to keep it backward compatible I load Crockfords JSON-library from cloudflare CDN if no native JSON support is given (for simplicity using jQuery):

function winHasJSON(){
  json_data = JSON.stringify(obj);
  // ... (do stuff with json_data)
}
if(Object.prototype.hasOwnProperty.call(window, "JSON") && typeof JSON.stringify === 'function'){
  winHasJSON();
} else {
  $.getScript('//cdnjs.cloudflare.com/ajax/libs/json2/20121008/json2.min.js', winHasJSON)
}

edited Jan 19 '23 at 12:19

answered Jun 01 '13 at 11:36

AvL

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`typeof JSON === "object"` is not a safe check. `if(typeof JSON === 'object' && typeof JSON.stringify === 'function')` will fail if, for whatever reason, `JSON === null`. You’re looking for an existence check. The correct way is `if(Object.prototype.hasOwnProperty.call(window, "JSON") && typeof JSON.stringify === "function")` (in modern browsers, it would be `Object.hasOwn(globalThis, "JSON")`, but, of course, modern browsers have `JSON`). According to [Edurne Pascual’s comment](/questions/558518/serializing-an-object-to-json/558534#comment13620495_558536), this check is actually redundant. – Sebastian Simon Jan 15 '23 at 12:40

score 0 · Answer 4 · answered Jan 15 '23 at 19:43

How to work with JSON in Javascript

Having to work with JSON is a common situation in web development, this is why Javascript provides the JSON object with its static methods.

Parsing from string to object

To parse a JSON string into a Javascript object we can use JSON.parse()

let obj = JSON.parse('{"x": 325, "y": 896, "speed": 16.5}')

Result:

obj = {
  x: 325,
  y: 896,
  speed: 16.5
}

Parsing from object to string

Converting a Javascript object to a string it's as easy as the inverse operation

let str = JSON.stringify({x: 325, y: 896, speed: 16.5})

Result:

str = '{"x": 325, "y": 896, "speed": 16.5}'

Serializing an object to JSON

4 Answers4

How to work with JSON in Javascript

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