Functions & Parameters — Free JavaScript Tutorial

Learn Functions & Parameters in JavaScript with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

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

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Sep 17, 2026

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Functions & Parameters in JavaScript

Function declaration: `function name(params) { ... }` — hoisted, can be called before definition.

Function expression: `const name = function(params) { ... }` — not hoisted.

Arrow function: `const name = (params) => expression` — concise, no own `this`.

Default parameters: `function greet(name="Student")` — used if argument is undefined.

Rest parameters: `function sum(...nums)` — collects all arguments into an array.

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