JSON Stringify

JSON Stringify

JSON.stringify() converts a JavaScript object or array into a JSON string.

The basics

const person = { name: "Ada", age: 36 };
const json = JSON.stringify(person);
// '{"name":"Ada","age":36}'

Why stringify?

• Send data to a server (it needs text).
• Save data in localStorage.
• Log or debug objects.

Stringifying arrays

JSON.stringify([1, 2, 3]); // "[1,2,3]"

What cannot be stringified

• Functions are omitted.
• undefined values are omitted.
• Symbols are omitted.

JSON.stringify({ a: function() {}, b: 5 });
// '{"b":5}'

Pretty printing

Pass a spacing number for readable output:

JSON.stringify(person, null, 2);

TL;DR

• JSON.stringify turns objects into JSON text.
• Send or store data as strings.
• Functions, undefined, and symbols are dropped.
• A spacing argument makes output readable.