Variables

In the previous section, you learned about how to add javascript to a html file. In this section, you will learn about variables.

What is a variable ?

A variable is a placeholder in memory. In JavaScript, to access values you would need variables.

There are three ways to declare variables in JavaScript which are: const, let and var.

const is used to declare a variable you cannot change. Changing the value of const will lead to an error.

Example,

main.js

const a = 1;

a = 3;          //this will result to an error 

To print a value on the JavaScript console. You use console.log.

To print the initial value would be:

main.js

console.log(a);

You use let to declare a variable you can change. But you cannot redeclare the same value with let.

Example,

main.js

let x = 1;

console.log(x);       //1

let x = 11;          //this would give an error because x has been declared already 

var is an older version used in declaring variables. Unlike let, var can be redeclared.

Example,

main.js

var y = 2;

console.log(y);          //2

var y = 5;
console.log(y);          //5