What is the difference between let, var, and const?

July 31, 2025

I-Hub Talent: The Best Full Stack Python Institute in Hyderabad

If you're looking for the best Full Stack Python training institute in Hyderabad, I-Hub Talent is your ultimate destination. Known for its industry-focused curriculum, expert trainers, and hands-on projects, I-Hub Talent provides top-notch Full Stack Python training to help students and professionals master Python, Django, Flask, Frontend, Backend, and Database Technologies.

At I-Hub Talent, you will gain practical experience in HTML, CSS, JavaScript, React, SQL, NoSQL, REST APIs, and Cloud Deployment, making you job-ready. The institute offers real-time projects, career mentorship, and placement assistance, ensuring a smooth transition into the IT industry.

Join I-Hub Talent’s Full Stack Python course in Hyderabad and boost your career with the latest Python technologies, web development, and software engineering skills. Elevate your potential and land your dream job with expert guidance and hands-on training!

In JavaScript, var, let, and const are used to declare variables, but they differ in scope, hoisting, and mutability.

1. Scope

var: Function-scoped. It is accessible anywhere within the function it’s declared in. If declared outside a function, it becomes globally scoped.
let and const: Block-scoped. They are only accessible within the block ({}) where they are defined, such as in loops or conditionals.

2. Hoisting

var: Is hoisted to the top of its scope and initialized with undefined, so it can be accessed before declaration (but not recommended).
let and const: Also hoisted, but not initialized. Accessing them before declaration causes a ReferenceError due to the temporal dead zone.

3. Reassignment & Redeclaration

var: Can be redeclared and reassigned.
let: Can be reassigned but not redeclared in the same scope.
const: Cannot be reassigned or redeclared. Must be initialized during declaration.

Note: For const, the variable binding is constant, not the value. If the value is an object or array, its contents can still be modified.

Summary:

Use let and const for modern code; prefer const by default and use let if reassignment is needed. Avoid var unless working with legacy code.

What is the DOM?

Visit I-HUB TALENT Training institute in Hyderabad

Search This Blog

Full Stack Python