@jsweb/truetype

Simple JS module to check types consistently and concisely.

Tests coverage at https://truetype.jsweb.app

Why?

Checking types in JavaScript is not so easy...

The builtin operators typeof, instanceof and other methods are not precise enough to report the exact type of a value.

So, this module aims to check types of variables with more useful returns.

New in v4.0.0

Now, its a full ES module, there is no UMD or CommonJS version.

ES modules are the new pattern in modern JS development, already supported in newer versions of Node.js and modern borwsers natively.

Backward compatibility is not a concern here. If you use a module bundler (like Webpack or Rollup) to transpile your code, the result will be compatible according to your setup.

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Installation

You can install with NPM, Yarn or Unpkg CDN:

npm i -S @jsweb/truetype

yarn add @jsweb/truetype

pnpm add @jsweb/truetype

Usage

ES6

Tree shaking (since v3.0.0):

1import { isInteger, isDate, isNotNull } from '@jsweb/truetype'

From CDN (installation not required)

1<script type="module">
2  import { isNumber } from 'https://unpkg.com/@jsweb/truetype'
3
4  const number = isNumber(1)
5</script>

Methods

isDefined(value: any): boolean

Check if a value is not undefined.

isNull(value: any): boolean

Check if value is null.

isNotNull(value: any): boolean

Check if value is not null.

isValid(value: any): boolean

Check if value is "valid" (is not null or undefined).

instance(value: any): string

Get the constructor name of the value.

Returns a string with a type name like Object, Array, String, Number, ...

Can be a native or custom constructor name.

1instance(1) // returns Number
2
3class Foo {
4  constructor(x) {
5    this.x = x
6  }
7}
8
9const bar = new Foo(1)
10
11instance(bar) // returns Foo

is(value: any, type: string): boolean

Check if value is of type.

Can be a native or custom constructor name.

1is({}, 'Object') // returns true
2is([], 'Array') // returns true
3is('foo', 'String') // returns true
4is(false, 'Boolean') // returns true
5// ...
6
7class Foo {
8  constructor(x) {
9    this.x = x
10  }
11}
12
13const bar = new Foo(1)
14
15is(bar, 'Foo') // returns true

isBoolean(value: any): boolean

Check if value is a boolean.

isString(value: any): boolean

Check if value is a string.

isNumber(value: any): boolean

Check if value is a number.

isInteger(value: any): boolean

Check if value is an integer number.

isFloat(value: any): boolean

Check if value is a float point number.

isObject(value: any): boolean

Check if value is an object.

isArray(value: any): boolean

Check if value is an Array.

isDate(value: any): boolean

Check if value is a Date object.

isRegExp(value: any): boolean

Check if value is a Regular Expression.

isFunction(value: any): boolean

Check if value is a function.

isEmpty(value: string | array | object): boolean

This is a bonus utility.

Check if value is empty.

Only for string, array and objects. Any other type will return false.