entries-array

Returns an array of the key-value pairs of an Object, Map, Array, or Typed Array. Useful for when you need the entries of a collection object but aren’t sure what type of collection you’ll be given.

Installation

Requires Node.js 7.0.0 or above.

npm i entries-array

API

The module exports a single function.

Parameters

1. Bindable: c (Array, iterator, Object, Map, Set, string, or Typed Array)
2. Optional: Object argument:
   • arrays / maps / sets (arrays of classes/strings): Arrays of classes and/or string names of classes that should be treated as equivalent to Array/Map/Set (respectively).
   • detectPairs (boolean): This option only has an effect when c is an Array of two-item pairs, such as [[1, 2], [3, 4]]. When detectPairs is set to false (the default behavior), the Array indexes will be used as the keys (the returned array will be [[0, [1, 2]], [1, [3, 4]]]). But if detectPairs is true, the module will interpret the first item in each pair as the entry key (a copy of the original array will be returned: [[1, 2], [3, 4]]).
   • inObj (boolean): Whether or not to act like the “in” operator by including inherited Object properties. Only takes effect if c is an Object (i.e. not another recognized type). Defaults to false.
   • reflectObj (boolean): Whether or not to include non-enumerable Object properties by using reflection. Only takes effect if c is an Object (i.e. not another recognized type). Defaults to false.
   • reverse (boolean): If true, then entries are returned in reverse order. Defaults to false.

Return Value

An array of two-element key-value pair arrays.

Examples

Arrays

const entries = require('entries-array')

entries(['a', 'b']) // [[0, 'a'], [1, 'b']]

// Supports the bind operator
['a', 'b']::entries() // [[0, 'a'], [1, 'b']]

Examples using an array of entries (key/value pairs):

const entries = require('entries-array')

const arr = [['key1', 'val1'], ['key2', 'val2']]

// Default behavior without the `detectPairs` option
entries(arr) // [[0, ['key1', 'val1']], [1, ['key2', 'val2']]]

// With `detectPairs` set to `true`
entries(arr, {detectPairs: true}) // [['key1', 'val1'], ['key2', 'val2']]

Objects

const entries = require('entries-array')

entries({key: 'value'}) // [['key', 'value']]

// Supports the bind operator
const obj = {key: 'value'}
obj::entries() // [['key', 'value']]

Inherited Object Properties

Include Object properties from the prototype chain by setting inObj to true:

const entries = require('entries-array')

function Cls () {}
Cls.prototype.key = 'value'

entries(new Cls(), {inObj: true}) // [['key', 'value']]

Non-Enumerable Object Properties

Include non-enumerable Object properties by setting reflectObj to true:

const entries = require('entries-array')

const obj = {}
Object.defineProperty(obj, 'key', {value: 'value', enumerable: false})

entries(obj, {reflectObj: true}) // [['key', 'value']]

Iterators

entries-array will treat an iterator as if it were an array of values. Each “key” will be an incrementing integer index that starts at zero.

const entries = require('entries-array')

function * gen () {
  yield 'a'
  yield 'b'
}

entries(gen()) // [[0, 'a'], [1, 'b']]

Maps

const entries = require('entries-array')

const map = new Map()
map.set('key', 'value')

entries(map) // [['key', 'value']]

Sets

entries-array will treat a Set like an array, and will add integer index keys starting at zero. Note that this behavior is different from that of the built-in Set.prototype.entries() method.

const entries = require('entries-array')

const set = new Set()
set.add('first')
set.add('second')

entries(set) // [[0, 'first'], [1, 'second']]

Strings

entries-array will treat a string like a character array.

const entries = require('entries-array')

entries('hi') // [[0, 'h'], [1, 'i']]

Typed Arrays

const entries = require('entries-array')

const typedArray = new Int32Array(new ArrayBuffer(4))

entries(typedArray) // [[0, 0]]

Related

• entries-iterator
• keys-iterator
• keys-array
• values-iterator
• values-array