Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/wizard04wsu/javascript-type-testing

Improved JavaScript type testing
https://github.com/wizard04wsu/javascript-type-testing

javascript module type-testing

Last synced: 17 days ago
JSON representation

Improved JavaScript type testing

Host: GitHub
URL: https://github.com/wizard04wsu/javascript-type-testing
Owner: wizard04wsu
Created: 2021-08-27T17:02:57.000Z (over 3 years ago)
Default Branch: main
Last Pushed: 2024-02-17T16:04:58.000Z (11 months ago)
Last Synced: 2024-02-17T17:24:22.874Z (11 months ago)
Topics: javascript, module, type-testing
Language: JavaScript
Homepage:
Size: 34.2 KB
Stars: 0
Watchers: 1
Forks: 0
Open Issues: 0
Metadata Files:
- Readme: README.md

Awesome Lists containing this project

README

        # Improved JavaScript Type Testing

A robust alternative to JavaScript's built-in type testing.

See the [test page](https://wizard04wsu.github.io/javascript-type-testing/test/test.htm) for examples.

---

## Type Names

This module uses an expanded set of type names that make no distinction between primitive values and objects. 

For example, `5` and `new Number(5)` are both of type "number".

| Type Name             | Values

| - | -

| array                 | `Array` objects

| bigint                | _bigint_ primitives

| boolean               | `false`, `true`, `Boolean` objects

| date                  | `Date` objects

| error                 | `Error` objects

| function              | `Function` objects

| map                   | `Map` objects

| nan                   | `NaN`, `Number` objects with value `NaN`

| null                  | `null`

| number                | _number_ primitives, `Number` objects; excludes `NaN` values

| object                | instances of `Object` that don't match another type in this list

| promise               | `Promise` objects

| regex                 | `RegExp` objects

| set                   | `Set` objects

| string                | _string_ primitives, `String` objects

| symbol                | _symbol_ primitives

| undefined             | `undefined`

| weakmap               | `WeakMap` objects

| weakset               | `WeakSet` objects

## Determine a Type

The **is()** function returns an object describing the type of its argument.

Syntax:

> **is**(_value_)

Returned object:

| Property              | Description

| - | -

| .**type**             | The type name used by this module.

| .**typeof**           | The value returned by the `typeof` operator.

| .**toStringTag**      | The name used by `Object.prototype.toString()`. `undefined` for primitives.

| .**constructorName**  | The name of the argument's constructor. `undefined` for primitives.

| .**isObject**         | True if the value is an object.

| .**isPrimitive**      | True if the value is a primitive.

## Type Testing

Each of the type-testing methods return a boolean indicating if the argument is of that type.

Syntax:

> is._typeTester_(_value_)

### Basics

| Method              | Tests for

| - | -

| is.**function**()   | instance of `Function`

| is.**object**()     | instance of `Object`

| is.**primitive**()  | primitives

| is.**null**()       | `null`

| is.**nullish**()    | `undefined`, `null`

| is.**undefined**()  | `undefined`

| is.**defined**()    | not `undefined`

### Booleans

| Method              | Tests for

| - | -

| is.**boolean**()    | `false`, `true`, instance of `Boolean`

| is.**falsy**()      | `false`, `undefined`, `null`, `NaN`, `0`, `-0`, `0n`, `""`, [`document.all`](https://developer.mozilla.org/en-US/docs/Web/API/Document/all#conversion_to_boolean)

| is.**truthy**()     | not falsy

### Numbers

| Method              | Tests for

| - | -

| is.**bigint**()     | _bigint_ primitive

| is.**date**()       | instance of `Date`

| is.**numberish**()  | _number_ primitive, instance of `Number`

_Numberish_ values can be more explicitly tested using the following methods:

| Method              | Tests for

| - | -

| is.**real**()       | real numbers

| is.**infinite**()   | `Infinity`, `-Infinity`

| is.**number**()     | real numbers, `Infinity`, `-Infinity`

| is.**nan**()        | `NaN`

Note that JavaScript doesn't always treat mathematical expressions of undefined or indeterminate form as you might expect. For example, `1/0` is an undefined form, but JavaScript evaluates it as `Infinity`.

### Text

| Method              | Tests for

| - | -

| is.**regex**()      | instance of `RegExp`

| is.**string**()     | _string_ primitive, instance of `String`

### Collections

| Method              | Tests for

| - | -

| is.**array**()      | instance of `Array`

| is.**map**()        | instance of `Map`

| is.**set**()        | instance of `Set`

| is.**weakmap**()    | instance of `WeakMap`

| is.**weakset**()    | instance of `WeakSet`

### Other Common Types

| Method              | Tests for

| - | -

| is.**error**()      | instance of `Error`

| is.**promise**()    | instance of `Promise`

| is.**symbol**()     | _symbol_ primitive

## Additional Methods

| Method                       | Description

| - | -

| is.**empty**(_value_)        | Tests if an object's `.length` or `.size` property equals zero.

| is.**of**(_value_, _class_)  | Tests if _value_ is an instance of _class_. (Same as using the `instanceof` operator.)