function isnumber
isnumber(x: unknown): x is number

True for number.

Returns true if the input is a number or NaN, otherwise false.

Examples

Input is a number

import { assertEquals } from "jsr:@std/assert";

assertEquals(isnumber(5), true);

Input is NaN

import { assertEquals } from "jsr:@std/assert";

assertEquals(isnumber(NaN), true);

Input is a string representing a number (not a number)

import { assertEquals } from "jsr:@std/assert";

assertEquals(isnumber('5'), false);

Input is undefined

import { assertEquals } from "jsr:@std/assert";

assertEquals(isnumber(undefined), false);

Input is null

import { assertEquals } from "jsr:@std/assert";

assertEquals(isnumber(null), false);

Parameters

x: unknown

The element to check.

Return Type

x is number

Returns true if x is a number or NaN.

Usage

import isnumber from "datatype/isnumber.ts";