Js Functions — Free Javascript Tutorial

TL;DR: Learn Js Functions in Javascript with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

Js Functions in Javascript

Functions are reusable blocks of code. JavaScript has multiple ways to define them: function declarations, function expressions, and arrow functions (ES6+).

Arrow functions (=>) are shorter and don't have their own this. For a single expression, the return is implicit: const add = (a, b) => a + b.

Default parameters: function greet(name = "Student") — if name is not passed, "Student" is used.

Rest parameters: function sum(...nums) collects all arguments into an array. The spread operator (...arr) does the opposite — expands an array into individual values.

// Function declaration
function add(a, b) { return a + b; }

// Arrow function (short)
const multiply = (a, b) => a * b;

// Arrow with implicit return (no braces, no return keyword)
const square = n => n * n;

// Default parameter
function greet(name = "Student") { return \

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