isNumber

Checks if a value is a number type.

const result = isNumber(value);

Usage

isNumber(value)

Use isNumber when you want to check if a value is a number.

import { isNumber } from 'es-toolkit';

// Checking basic number values
isNumber(123); // true
isNumber(3.14); // true
isNumber(NaN); // true
isNumber(Infinity); // true

// Distinguishing from other types
isNumber('123'); // false
isNumber(true); // false
isNumber(null); // false
isNumber(undefined); // false

Particularly useful when used as a type guard in TypeScript.

import { isNumber } from 'es-toolkit';

function processValue(value: unknown) {
  if (isNumber(value)) {
    // value is narrowed to number
    console.log(value * 2);
  } else {
    console.log('Not a number');
  }
}

Parameters

• value (unknown): The value to check if it's a number type.

Returns

(value is number): Returns true if the value is a number, false otherwise.