JavaScript JSON Reference

JSON (JavaScript Object Notation)

JSON is a format for storing and transporting data.

JSON is text, and text can be transported anywhere, and read by any programming language.

JavaScript Objects can be converted into JSON, and JSON can be converted back into JavaScript Objects.

This way we can work with the data as JavaScript objects, with no complicated parsing or translations.

Example

Sending JSON:

// a JavaScript object...:
var myObj = { "name":"John", "age":31, "city":"New York" };

// ...converted into JSON:
var myJSON = JSON.stringify(myObj);

// send JSON:
window.location = "demo_json.php?x=" + myJSON;

Try it Yourself »

For a tutorial about JSON, read our JSON Tutorial.

JSON Methods

Method	Description
parse()	Parses a JSON string and returns a JavaScript object
stringify()	Convert a JavaScript object to a JSON string

Valid Data Types

In JSON, values must be one of the following data types:

a string
a number
an object (containing valid JSON values)
an array
a boolean
null

JSON values cannot be one of the following data types:

a function
a date
undefined

More Examples

Example

Receiving JSON:

// myJSON is text received in JSON format.
// Convert JSON into a JavaScript object:
var myObj = JSON.parse(myJSON);
document.getElementById("demo").innerHTML = myObj.name;

Try it Yourself »

Example

Storing data as JSON, using localStorage

// Storing data:
myObj = { "name":"John", "age":31, "city":"New York" };
myJSON = JSON.stringify(myObj);
localStorage.setItem("testJSON", myJSON);

// Retrieving data:
text = localStorage.getItem("testJSON");
obj = JSON.parse(text);
document.getElementById("demo").innerHTML = obj.name;

Try it Yourself »

Learn more about JSON in our JSON tutorial.

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