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@arrows/dispatch

Table of contents

1. Introduction
2. Installation
3. API reference
   • getType
   • identity
   • is
   • isIn
   • types
4. License

Introduction

The library contains a collection of dispatch functions. All functions with the arity (number of arguments) greater than one are automatically curried, so a partial application is possible.

The library has built-in type definitions, which provide an excellent IDE support.

Installation

Via NPM:

npm i @arrows/dispatch

Via Yarn:

yarn add @arrows/dispatch

All modules can be imported independently (to reduce bundle size), here are some import methods (you can use either CommonJS or ES modules):

import dispatch from '@arrows/dispatch'

import { getType } from '@arrows/dispatch'

import getType from '@arrows/dispatch/getType'

API reference

getType

Retrieves the type of a value (using the internal [[Class]] property). A more useful alternative for the typeof operator.

It does not return custom prototypes - if you need that, use the is function instead.

See: types for the list of the most common values.

See: MDN - Object.prototype.toString.call

Parameters

• value - Any value

Returns

• Returns an underlying class as a string.

Interface

(value) => underlying_class_name

Example

getType(1) // -> "Number"
getType(/abc/) // -> "RegExp"
getType([1, 2, 3]) // -> "Array"

---

identity

Standard identity function - useful as a default dispatch or a placeholder.

Parameters

• value - Any value

Returns

• Returns the argument as-is.

Interface

(value) => value

Example

identity('foo') // -> "foo"
identity([1, 2, 3]) // -> [1, 2, 3]

---

is

Checks if a value is an instance of a prototype/class.

Parameters

• prototype - A prototype/class with which you want to check the value.
• value - Any value

Returns

• Returns true is a value is an instance of a prototype/class, false otherwise.

Interface

(prototype, value) => boolean

Example

class Cat {}
class Dog {}

const cat = new Cat()
const dog = new Dog()

is(Cat, cat) // -> true
is(Dog, cat) // -> false

is(Cat)(cat) // -> true
is(Dog)(cat) // -> false

---

isIn

Checks if a value is inside an array/set.

Parameters

• list - An array or a set of values
• value - Any value

Returns

• Returns true is a value is inside an array/set, false otherwise.

Interface

(array_or_set, value) => boolean

Examples

const names = ['Alice', 'Joe', 'John']

isIn(names, 'Alice') // -> true
isIn(names, 'Bob') // -> false

isIn(names)('Alice') // -> true
isIn(names)('Bob') // -> false

const names = new Set(['Alice', 'Joe', 'John'])

isIn(names, 'Alice') // -> true
isIn(names, 'Bob') // -> false

isIn(names)('Alice') // -> true
isIn(names)('Bob') // -> false

---

types

An object that contains a list of the most common types to use with the getType function. You can use it instead of using raw strings (which is error-prone).

Example

getType([1, 2, 3]) === types.Array // -> true

getType(() => null) === types.Function // -> true

getType(Promise.resolve()) === types.Promise // -> true

getType('1') === types.Number // -> false

License

Project is under open, non-restrictive ISC license.

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