is-lite

Type check tool (just 0.6k minified+gzipped)

Setup

npm install is-lite

Usage

import is from 'is-lite';

const value = '';

is.string(value) // true;

API

is(value)

Returns the type of the value.

Primitives are lowercase: bigint, boolean, null, number, string, symbol, undefined
The rest are camelcase: Array, Function, GeneratorFunction, Object, ...

####is.array(value)

####is.asyncFunction(value)

Check if value is an async function that can be called with await

is.asyncFunction(async () => {}); // => true
is.asyncFunction(() => {}); // => false

####is.boolean(value)

####is.date(value)

####is.domElement(value)
Check if value is a DOM Element.

####is.error(value)

####is.function(value)

####is.generator(value)
Check for an object that has its own .next() and .throw() methods and has a function definition for Symbol.iterator

####is.generatorFunction(value)

####is.instanceOf(value, class) Check if value is a direct instance of class

class APIError extends Error {}

const error = new APIError('Fail');

is.instanceOf(error, APIError); // true 
is.instanceOf(error, Error); // false 

####is.iterable(value)

####is.map(value)

####is.nan(value)

####is.null(value)

####is.nullOrUndefined(value)

####is.number(value)
Note: is.number(NaN) returns false

####is.numericString(value) Check for a string that represents a number. For example, '42' and '-8'. Note: 'NaN' returns false, but 'Infinity' and '-Infinity' return true

####is.object(value) Remember that functions and arrays are objects too.

####is.plainObject(value) Check if the object is created by either {}, new Object(), or Object.create(null).

####is.promise(value)

####is.regexp(value)

####is.set(value)

####is.string(value)

####is.symbol(value)

####is.undefined(value)

####is.weakMap(value)

####is.weakSet(value)

FAQ

@sindresorhus/is is amazing but I needed something even smaller (and simpler). This package cover the basics and is only 0.6k minified+gzipped.