6 Ways to Declare a Variable in JavaScript

var, let, const, function, class, import, and more

Photo by the author, Neptun Romania

It is used to say that in JavaScript variables can be declared with var, let and const, but if you think about it, the function declaration, the class declaration, and the import statement are also ways to declare variables. This article looks at all of them.

var

var allows to declares variables that can be reassigned. Nonetheless, it has a few problems:

• Variables can be used before declaration. The declarations are hoisted to the top of their scope. When used before declaration variables have the value of undefined.
• Variables can be redeclared in the same sope. This approach basically reassigns the existing variable.
• It does not have black scope.

Here is an example.

var x = 1;

var declarations have become obsolete.

let

let declares a variable that can be reassigned. Variables declared with let cannot be used before declarations and cannot be redeclared in the same scope. It can have block scope. It basically fixes the problems of the var declaration.