JSON Functions in JavaScript —

Imagine you are a JavaScript learner building a small website. You want to send a user’s information to a server and receive information from an API. How can you convert JavaScript data into a format that can be sent and read easily?

Meet your new friend: JSON!

Add to Favorites

1. What is JSON?

JSON stands for JavaScript Object Notation. It is a text format used to store and exchange data.

Imagine you have a student named Raveena. You want to store her details:

JavaScript

const student = {
  name: "Raveena",
  age: 18,
  subject: "JavaScript"
};

This is a JavaScript object. JSON helps you convert data into a text format that different applications can exchange.

2. The two main JSON functions

Add to Favorites

A. JSON.stringify() — Object to String

Think of it as a packing machine. It packs a JavaScript object into a JSON string.

JavaScript

const student = { name: "Raveena" };

const text = JSON.stringify(student);
console.log(text);
// {"name":"Raveena"}

Add to Favorites

B. JSON.parse() — String to Object

Think of it as an unpacking machine. It converts valid JSON text back into a JavaScript value.

JavaScript

const text = '{"name":"Raveena"}';

const student = JSON.parse(text);
console.log(student.name);
// Raveena

3. Story diagram: How JSON works

JavaScript Object

Get Raveenanagar’s stories in your inbox

Join Medium for free to get updates from this writer.

Remember me for faster sign in

{ name: "Raveena" }

JSON.stringify()

Converts object into text

JSON String

'{"name":"Raveena"}'

JSON.parse()

Converts text back into an object

4. Other useful JSON features

• JSON.stringify() with a replacer: lets you choose which properties to include.
• JSON.parse() with a reviver: lets you transform values while parsing.

Example of selecting properties:

JavaScript

const student = {
  name: "Raveena",
  age: 18,
  city: "Kota"
};

const result = JSON.stringify(student, ["name", "city"]);
console.log(result);
// {"name":"Raveena","city":"Kota"}

5. Try it yourself!

Question: You have a JSON string and want to convert it into a JavaScript object. Which function will you use?

A. JSON.stringify()

B. JSON.parse()

C. console.log()

Check answer

Remember the story

• JSON.stringify() = Pack an object into a string.
• JSON.parse() = Unpack a JSON string into a value.
• JSON is commonly used when exchanging data between websites, servers, and APIs.

Small functions, big possibilities! 🚀