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 »
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;
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 »
// Convert JSON into a JavaScript object:
var myObj = JSON.parse(myJSON);
document.getElementById("demo").innerHTML = myObj.name;
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 »
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;
Learn more about JSON in our JSON tutorial.