Difference Between Var, Let, Const In JavaScript

Var

Var creates a variable that is function-scoped and can be reassigned at any time. If a var variable is declared outside of a function, it is part of the global scope and will be a property on the global object.

Example

//Example 1
var language = "javascript";
language = "JavaScript is the world's most popular programming language"; // New Value Assigned
console.log(language);
//Output
//JavaScript is the world's most popular programming language
//Example 2
function LanguageExample() {
    var likes = 500;
    console.log(likes); //Output:- 500
}
console.log(likes); //ReferenceError: likes is not defined (we can not access outside the function . only accessible inside function)

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Let

A variable declared with let can be reassigned at any time. let is block scoped, which means it is only available within the function.

Example

function LanguageExample() {
    let likes = 500;
    console.log(likes); //Output:- 500
}
console.log(likes); //ReferenceError: likes is not defined (Unable to access outside the function block)

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const

const is used for constant values. Hence, they cannot be reassigned. They are block scoped, just like let.

Example

// Example 1
const language = "javascript";
language = "JavaScript is the world's most popular programming language"; // Uncaught TypeError: Assignment to constant variable.
//Example 2
function LanguageExample() {
    const likes = 500;
    console.log(likes); //Output:- 500
}
console.log(likes); //ReferenceError: likes is not defined

JavaScript

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