---
title: "What is the difference between var, let, and const in JavaScript? - GreatStack Forum"
url: "https://greatstack.dev/forum/post/what-is-the-difference-between-var-let-and-const-in-javascript-Ebeaq"
type: "forum_post"
author: "Dev Hacker"
date: "2026-03-29"
tags:
  - "javascript"
  - "webdevelopment"
  - "beginners"
  - "coding"
---
# What is the difference between var, let, and const in JavaScript?

**Dev Hacker** · 2026-03-29 · Score: +1 · 💬 0 comments · 👁 20 views

Tags: `javascript`, `webdevelopment`, `beginners`, `coding`

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Understanding variable declaration is very important in JavaScript.

Here are the key differences:

1. var:

- Function scoped

- Can be redeclared

- Hoisted with undefined

2. let:

- Block scoped

- Cannot be redeclared

- Can be updated

3. const:

- Block scoped

- Cannot be updated or redeclared

- Must be initialized

Example:

var a = 10;

let b = 20;

const c = 30;

In modern JavaScript, it is recommended to use let and const instead of var.

Which one do you use the most and why?

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_Read and discuss at [GreatStack](https://greatstack.dev/forum/post/what-is-the-difference-between-var-let-and-const-in-javascript-Ebeaq)._