📦 JSON (JavaScript Object Notation)

Last Updated: 26th October 2025

JSON is a lightweight data format used to store and exchange data.
It is text-based and language-independent, but easily usable in JavaScript.

Hinglish Tip 🗣: JSON ko samjho ek "structured text format" jaise notebook me table bana ho aur usko easily share kar sake.

Syntax Rules

  1. Data is in key-value pairs.
  2. Keys must be strings inside double quotes "key".
  3. Values can be:
    • String → "value"
    • Number → 100
    • Boolean → true / false
    • Null → null
    • Array → [1, 2, 3]
    • Object → {"key":"value"}
  4. No trailing commas allowed.

Example 1: Simple JSON Object

let person = {
  name: "Amit",
  age: 25,
  isStudent: true,
  hobbies: ["reading", "traveling", "coding"],
  address: {
    city: "Delhi",
    zip: "110001",
  },
};

console.log(person.name); // Amit
console.log(person.hobbies[1]); // traveling
console.log(person.address.city); // Delhi

Example 2: JSON Array

let users = [
  { name: "Amit", age: 25 },
  { name: "Suraj", age: 30 },
  { name: "Rahul", age: 35 },
];

console.log(users[1].name); // Suraj
console.log(users[2].age); // 35

Converting Between JSON and JavaScript Objects

  1. JSON.stringify()

Converts a JavaScript object/array into JSON string.

let user = { name: "Sadhu", age: 1 };

let json = JSON.stringify(user);
console.log(json); // {"name":"Sadhu","age":1}
  1. JSON.parse()

Converts a JSON string into a JavaScript object.

let json = '{"name":"Sadhu","age":1}';

let user = JSON.parse(json);
console.log(user); // {name: "Sadhu", age: 1}

Hinglish Tip 🗣: stringify() → JS object ko text banata hai, parse() → text ko JS object me badalta hai.

💡 Quick Practice

  • Create a JSON object for a book with title, author, price, and genres (array).
  • Convert it to JSON string and then parse it back to JS object.
  • Access nested properties like genres[1] or author.
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