How to check if a string is a number in JavaScript?

February 1, 2022

To check if a string is a number JavaScript, do this: !isNaN(string).

Here's how you do it:

const twoIsNumber = !isNaN('2');
const twoPointFiveIsNumber = !isNaN('2.5');
const helloWorldIsNumber = !isNaN('Hello World!');

console.log(twoIsNumber); // true
console.log(twoPointFiveIsNumber); // true
console.log(helloWorldIsNumber); // false