is.js

Javascript checking library.

Installation

npm install --save @abhaydgarg/is

Run test

# all
npm run test

# single file
FILE=is-string.test.js npm run test:file

Usage

// commonJS - Destructuring
const { isEmpty, isString } = require('@abhaydgarg/is');

// ES6 - using webapack bundler
import { isEmpty, isString } from '@abhaydgarg/is';

API

1. Type check

isArray(value)

Check if value is of type Array.

isBoolean(value)

Check if value is of type boolean.

isDate(value)

Check if value is of type Date.

isError(value)

Check if value is of type Error.

isFunction(value)

Check if value is of type function.

isMap(value)

Check if value is of type Map.

isNumber(value)

Check if value is of type number.

isObject(value)

Check if value is of type object.

isRegEx(value)

Check if value is of type RegExp.

isSet(value)

Check if value is of type Set.

isString(value)

Check if value is of type string.

isSymbol(value)

Check if value is of type symbol.

isUndefined(value)

Check if value is undefined.

isNull(value)

Check if value is null.

isNullOrUndefined(value)

Check if value is either null or undefined.

2. Emptiness check

isEmpty(value)

Check if value is empty.

All below return true

isEmpty(null);
isEmpty(undefined);
isEmpty(function () { }); // empty function
isEmpty([]); // array length 0
isEmpty(new Error()); // without message
isEmpty(new Set()); // Set size 0
isEmpty(new Map()); // Map size 0
isEmpty({});
isEmpty(0);
isEmpty(''); // string length 0
isEmpty(' ') // whitespace string is consider empty

3. Value check

isNumeric(value)

Check if value is numeric.

isNumeric(1234567890); // true
isNumeric('1234567890'); // true
isNumeric('-123'); // true
isNumeric('1.23'); // true
isNumeric('Infinity'); // true
isNumeric('0xFF') // true
isNumeric('123e5');  // true

isInteger(value)

Check if value of type number is integer (whole number).

isFloat(value)

Check if value of type number is float (fractional number).

isUrl(value)

Check if value is url.

isEmail(value)

Check if value is email.

isWhitespace(value)

Check if value of type string is whitespace.

License

MIT