How to Declare a Variable in JavaScript ?

Variables are the heart of any programming language. In JavaScript, there are multiple ways available to declare a variable using different keywords like let, const, and var.

• var: Before ES6 or ES2015, it was the only way to declare variables in JavaScript. It declares variables in the global scope.
• let: It was introduced in ES6, It is used to declare variables in block scope.
• const: It was also introduced in ES6 to declare the constant variable whose values are not going to change throughout the code.

Example: The below code shows how you can declare variables using these keywords.

Javascript

var name = "GeeksforGeeks";
console.log(name);
var name = "Virat Kohli"; // Allowed
console.log(name);

let desc = "A Computer Science Portal.";
// let desc = "26000 International Runs."; // Not Allowed,
// Error: Identifier 'desc' has already been declared
console.log(desc);

const workForce = 200;
console.log(workForce);
// const workForce; // Not Allowed,
// Error: Missing initializer in const declaration

Output

GeeksforGeeks
Virat Kohli
A Computer Science Portal.
200