JavaScript variables and constants

A variable gives a name to a value so your program can use it later.

What you will learn

How to declare a value with let or const
When reassignment is allowed

Minimal example

let count = 0; count = count + 1; const siteName = 'Yugien';

Use let when a variable needs a new value and const when the binding should not be reassigned.

Common mistakes

const prevents reassignment, but it does not make every object immutable.
Prefer let and const in new code instead of var.