How to Determine if a Value is a Number in JavaScript

In JavaScript, there are multiple ways to check if a variable value is a number. Let’s explore two common approaches.

Method 1: Using isNaN() Function

JavaScript provides a global function called isNaN() that can be used to check if a value is a number. This function is assigned to the window object in the browser environment. Here’s an example:

const value = 2;

isNaN(value); // returns false

isNaN('test'); // returns true

isNaN({}); // returns true

isNaN(1.2); // returns false

If the isNaN() function returns false, it means the value is a number.

Method 2: Using the typeof Operator

Another way to check if a value is a number in JavaScript is by using the typeof operator. When used on a number value, the typeof operator returns the string 'number'. Here’s an example:

typeof 1; // returns 'number'

const value = 2;

typeof value; // returns 'number'

You can use this approach for conditional checks, like so:

const value = 2;
if (typeof value === 'number') {
  // it's a number
}

By applying these methods, you can easily determine if a value is a number in JavaScript.

Tags: JavaScript, Number Checking