Check if a variable is a Number in JavaScript

In this tutorial, we are going to learn about two different ways to check if a variable is a number in JavaScript.

Using typeof operator

To check if a variable is a number, we can use the typeof operator in JavaScript.

The typeof operator returns the type of a given variable in string format.

Example:

let a = 11;

if (typeof a === 'number') {
    console.log('variable is a number');
} else {
    console.log('variable is not a number');
}

Output:

"variable is a number"

Using Number.isInteger() method

Similarly, we can also use the Number.isInteger() method in JavaScript to check if a variable is a Number or not.

The Number.isInteger() method returns true if a provided variable is a number, otherwise it returns false.

Here is an exmaple:

let a = 11;
let b = "king";

if (Number.isInteger(a)) {
  console.log('a is number');
} else {
  console.log('a is not a number');
}

False case:

let a = 11;
let b = "king";

// it logs not a number
if (Number.isInteger(b)) {
  console.log('b is number');
} else {
  console.log('b is not a number');
}