identitate

A tiny custom identity function creator for composable softwares.

Table of contents

- Usage
- Pre-built methods
- identity
- identitySecond
- identityLast
- identitySecondLast
- Custom methods
- createIdentity
- Browser support
- Development

Usage

``javascript
import { createIdentity, identity, identitySecond, identityLast, identitySecondLast } from 'identitate';

// use built-in methods
console.log(identity('first', 'second', 'third', 'fourth', 'fifth')); // 'first'
console.log(identitySecond('first', 'second', 'third', 'fourth', 'fifth')); // 'second'
console.log(identityLast('first', 'second', 'third', 'fourth', 'fifth')); // 'fifth'
console.log(identitySecondLast('first', 'second', 'third', 'fourth', 'fifth')); // 'fourth'

// or create your own
const identityThird = createIdentity(2);
const identityThirdLast = createIdentity(-3);
const identityFirstNested = createIdentity(0, 'deeply[0].nested');

console.log(identityThird('first', 'second', 'third', 'fourth', 'fifth')); // 'third'
console.log(identityThirdLast('first', 'second', 'third', 'fourth', 'fifth')); // 'third'
console.log(identityFirstNested({ deeply: [{ nested: 'value' }] }, 'second', 'third', 'fourth', 'fifth')); // 'value'
`

Pre-built methods

#### identity

_returns first argument passed to it_

The classic identity function:

`javascript
console.log(identity('first', 'second', 'third', 'fourth', 'fifth')); // 'first'
`

#### identitySecond

_returns second argument passed to it_

`javascript
console.log(identitySecond('first', 'second', 'third', 'fourth', 'fifth')); // 'second'
`

Example usage when creating meta properties with the popular redux-actions package:

`javascript
import { identity, identitySecond } from 'identitate';
import { createAction } from 'redux-actions';

export const doThing = createAction('DO_THING', identity, identitySecond);

console.log(doThing('payload', 'meta')); // {meta: 'meta', payload: 'payload', type: 'DO_THING'}
`

#### identityLast

_returns last argument passed to it, regardless of total number of arguments_

`javascript
console.log(identityLast('first', 'second', 'third', 'fourth', 'fifth')); // 'fifth'
console.log(identityLast('first', 'second', 'third')); // 'third'
`

#### identitySecondLast

_returns second-to-last argument passed to it, regardless of total number of arguments_

`javascript
console.log(identitySecondLast('first', 'second', 'third', 'fourth', 'fifth')); // 'fourth'
console.log(identitySecondLast('first', 'second', 'third')); // 'second'
`

Custom methods

#### createIdentity

_creates a new identity method based on the parameters passed_

createIdentity(position: number[, path: (Array|number|string)]): any

`javascript
// use a positive number to get the index of the arguments (zero-indexed)
const identityFourth = createIdentity(3);

console.log(identityLast('first', 'second', 'third', 'fourth', 'fifth')); // 'fourth'

// use a negative number to get the index of the arguments relative to the last
const identityThirdLast = createIdentity(-3);

console.log(identityLast('first', 'second', 'third', 'fourth', 'fifth')); // 'third'

// include a path to get the deeply-nested value of that argument
const identityNested = createIdentity(0, 'deeply.nested');

console.log(identityNested({ deeply: { nested: 'value' } })); // 'value'
`

The path parameter uses pathington under the hood for path parsing, so
check there for valid values.

Browser support

- Chrome (all versions)
- Firefox (all versions)
- Edge (all versions)
- Opera 15+
- IE 9+
- Safari 6+
- iOS 8+
- Android 4+

Development

Standard stuff, clone the repo and npm install dependencies. The npm scripts available:

- build => run webpack to build development dist file with NODE_ENV=development
- build:minified => run webpack to build production dist file with NODE_ENV=production
- dev => run webpack dev server to run example app / playground
- dist => runs build and build-minified
- lint => run ESLint against all files in the src folder
- prepublish => runs compile-for-publish
- prepublish:compile => run lint, test:coverage, transpile:es, transpile:lib, dist
- test => run AVA test functions with NODE_ENV=test
- test:coverage => run test but with nyc for coverage checker
- test:watch => run test, but with persistent watcher
- transpile:lib => run babel against all files in src to create files in lib
- transpile:es => run babel against all files in src to create files in es, preserving ES2015 modules (for
pkg.module`)