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JSON Syntax in JavaScript (Live Playground)

JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy to read and write. It is used to represent data structures in a human-readable and language-independent format. JSON is often used to transmit data between a server and a web application, or between different parts of a program. In this tutorial, we will explore the JSON syntax and how to work with it in JavaScript.

JSON Syntax in JavaScript

JSON syntax is a subset of JavaScript object literal notation. However, there are some differences and restrictions:

  • Data is represented in key-value pairs.
  • Keys must be strings, and they must be wrapped in double quotes (").
  • Values can be strings, numbers, booleans, objects, arrays, or null.
  • Strings must also be wrapped in double quotes (").
  • No functions or methods are allowed.


"firstName": "John",
"lastName": "Doe",
"age": 30,
"isStudent": true,
"courses": ["Math", "Physics", "Chemistry"],
"address": {
"city": "New York",
"state": "NY"

Working with JSON in JavaScript

JavaScript provides two methods for working with JSON data:

  • JSON.parse(): Parses a JSON string and returns a JavaScript object.
  • JSON.stringify(): Converts a JavaScript object to a JSON string.


const jsonString = '{"firstName":"John","lastName":"Doe","age":30}';

const jsObject = JSON.parse(jsonString);
console.log(jsObject.firstName); // Output: John

const newJsonString = JSON.stringify(jsObject);
console.log(newJsonString); // Output: {"firstName":"John","lastName":"Doe","age":30}
Live Playground, Try it Yourself


Understanding JSON syntax and how to work with JSON data in JavaScript is essential for modern web development. JSON allows you to represent data structures in a simple, human-readable format, making it easy to transmit and store data.