Example 1: javascript check if number
//Updated dec 2020 // The first 2 Variations return a Boolean // They just work the opposite way around // IsInteger if (Number.isInteger(val)) { // It is indeed a number } // isNaN (is not a number) if (isNaN(val)) { // It is not a number } // Another option is typeof which return a string if (typeof(val) === 'number') { // Guess what, it's a bloody number! }
Example 2: javascript check if number
function isNumber(n) { return /^-?[\d.]+(?:e-?\d+)?$/.test(n); } ------------------------ isNumber('123'); // true isNumber('123abc'); // false isNumber(5); // true isNumber('q345'); // false isNumber(null); // false isNumber(undefined); // false isNumber(false); // false isNumber(' '); // false
Example 3: To check if a value is a number in JavaScript
const value = 2 isNaN(value) //false isNaN('test') //true isNaN({}) //true isNaN(1.2) //false
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