is-number
In JavaScript, itβs not always as straightforward as it should be to reliably
check if a value is a number. Itβs common for devs to use +
, -
, or Number()
to
cast a string value to a number (for example, when values are returned from user
input, regex matches, parsers, etc). But there are many non-intuitive edge cases
that yield unexpected results:
console.log(+[]); //=> 0
console.log(+""); //=> 0
console.log(+" "); //=> 0
console.log(typeof NaN); //=> 'number'
Usage
Deno π¦
import { isNumber } from "https://deno.land/x/is_number/mod.ts";
isNumber("hello")); //=> false
isNumber("678")); //=> true
isNumber({}) //=> false
isNumber(+{a:"34"}) //=> false
isNumber(345)); //=> true
Node.js π’
import { isNumber } from "@ultirequiem/is-number";
Browser
Using type module π±
Using a plain script tag π
You have the same API on all of this platforms.
Documentation
True Cases
isNumber(5e3);
isNumber(0xff);
isNumber(-1.1);
isNumber(0);
isNumber(1);
isNumber(1.1);
isNumber(10);
isNumber(10.1);
isNumber(100);
isNumber("-1.1");
isNumber("0");
isNumber("012");
isNumber("0xff");
isNumber("1");
isNumber("1.1");
isNumber("10");
isNumber("10.10");
isNumber("100");
isNumber("5e3");
isNumber(parseInt("012"));
isNumber(parseFloat("012"));
False cases
Everything else is false.
isNumber(Infinity);
isNumber(NaN);
isNumber(null);
isNumber(undefined);
isNumber("");
isNumber(" ");
isNumber("foo");
isNumber([1]);
isNumber([]);
isNumber(function () {});
isNumber({});
See the tests for more examples.
Support
Open an Issue, I will check it a soon as possible π
If you want to hurry me up a bit send me a tweet π
Consider supporting me on Patreon if you like my work π
Donβt forget to start the repo β
Licence
Licensed under the MIT License.