You don't (may not) need Lodash/Underscore


Lodash and Underscore are great modern JavaScript utility libraries, and they are widely used by Front-end developers. However, when you are targeting modern browsers, you may find out that there are many methods which are already supported natively thanks to ECMAScript5 [ES5] and ECMAScript2015 [ES6]. If you want your project to require fewer dependencies, and you know your target browser clearly, then you may not need Lodash/Underscore.

You are welcome to contribute with more items provided below.

* If you are targeting legacy JavaScript engine with those ES5 methods, you can use es5-shim

* Please note that, the examples used below are just showing you the native alternative of performing certain tasks. For some functions, Lodash provides you more options than native built-ins. This list is not a 1:1 comparison.

* Please send a PR if you want to add or modify the code. No need to open an issue unless it's something big and you want to discuss.

Voice of Developers

> Make use of native JavaScript object and array utilities before going big.

> —Cody Lindley, Author of jQuery Cookbook and JavaScript Enlightenment


> You probably don't need Lodash. Nice List of JavaScript methods which you can use natively.

> —Daniel Lamb, Computer Scientist, Technical Reviewer of Secrets of the JavaScript Ninja and Functional Programming in JavaScript


> I guess not, but I want it.

> —Tero Parviainen, Author of build-your-own-angular


> I'll admit, I've been guilty of overusing #lodash. Excellent resource.

> —@therebelrobot, Maker of web things, Facilitator for Node.js/io.js

ESLint Plugin

If you're using ESLint, you can install a
plugin that
will help you identify places in your codebase where you don't (may not) need Lodash/Underscore.

Install the plugin ...

``sh
npm install --save-dev eslint-plugin-you-dont-need-lodash-underscore
`

... then update your config

`json
"extends" : ["plugin:you-dont-need-lodash-underscore/compatible"],
`

For more information, see Configuring the ESLint Plugin

> [!IMPORTANT]
> Note that, while many Lodash methods are null safe (e.g. _.keys, _.entries),
> this is not necessarily the case for their Native equivalent. If null safety is critical for your application, we
> suggest that you take extra precautions [e.g. consider using the native Object.keys as Object.keys(value || {})].

Quick Links

Array

1. _.chunk
1. _.compact
1. _.concat
1. _.difference
1. _.drop
1. _.dropRight
1. _.fill
1. _.find
1. _.findIndex
1. _.first
1. _.flatten
1. _.flattenDeep
1. _.fromPairs
1. _.head and _.tail
1. _.indexOf
1. _.intersection
1. _.isArray
1. _.isArrayBuffer
1. _.join
1. _.last
1. _.lastIndexOf
1. _.reverse
1. _.slice
1. _.without
1. _.initial
1. _.pull
1. _.unionBy

Collection*

> [!IMPORTANT]
> Note that most native equivalents are array methods,
> and will not work with objects. If this functionality is needed and no object method is provided,
> then Lodash/Underscore might be the better option. Bear in mind however, that all iterable
> objects can easily be converted to an array by use of the
> spread operator.

1. _.each
1. _.every
1. _.filter
1. _.groupBy
1. _.includes
1. _.keyBy
1. _.map
1. _.minBy and _.maxBy
1. _.orderBy
1. _.pluck
1. _.range
1. _.reduce
1. _.reduceRight
1. _.reject
1. _.size
1. _.some
1. _.sortBy
1. _.uniq
1. _.uniqWith

Function

1. _.after
1. _.bind
1. _.debounce
1. _.isFunction
1. _.partial
1. _.throttle

Lang

1. _.castArray
1. .cloneDeep
1. _.gt
1. _.gte
1. _.isDate
1. _.isEmpty
1. _.isFinite
1. _.isInteger
1. _.isNaN
1. _.isNil
1. _.isNull
1. _.isUndefined

Object

1. _.assign
1. _.defaults
1. _.extend
1. _.has
1. _.get
1. _.invert
1. _.isPlainObject
1. _.keys
1. _.mapKeys
1. _.omit
1. _.pick
1. _.pickBy
1. _.toPairs
1. _.values

String

1. _.capitalize
1. _.endsWith
1. _.isString
1. _.lowerFirst
1. _.padStart and _.padEnd
1. _.repeat
1. _.replace
1. _.split
1. _.startsWith
1. _.template
1. _.toLower
1. _.toUpper
1. _.trim
1. _.upperFirst

Util

1. _.times

Number

1. _.clamp
2. _.inRange
3. _.random

Array

$3

Creates an array of elements split into groups the length of size.
`js
// Underscore/Lodash
_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]


// Native

const chunk = (input, size) => {
return input.reduce((arr, item, idx) => {
return idx % size === 0
? [...arr, [item]]
: [...arr.slice(0, -1), [...arr.slice(-1)[0], item]];
}, []);
};

chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]
`

#### Browser Support for Spread in array literals

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |

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$3

Creates an array with all falsy values removed.

`js
// Underscore/Lodash
_.compact([0, 1, false, 2, '', 3]);
// output: [1, 2, 3]

// Native
[0, 1, false, 2, '', 3].filter(Boolean)
// output: [1, 2, 3]
`

#### Browser Support for array.prototype.filter

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

Creates a new array concatenating array with any additional arrays and/or values.

`js
// Underscore/Lodash
var array = [1]
var other = _.concat(array, 2, [3], [[4]])

console.log(other)
// output: [1, 2, 3, [4]]

// Native
var array = [1]
var other = array.concat(2, [3], [[4]])

console.log(other)
// output: [1, 2, 3, [4]]
`

#### Browser Support for Array.prototype.concat()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |

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$3

Similar to without, but returns the values from array that are not present in the other arrays.

`js
// Underscore/Lodash
console.log(_.difference([1, 2, 3, 4, 5], [5, 2, 10]))
// output: [1, 3, 4]

// Native
var arrays = [[1, 2, 3, 4, 5], [5, 2, 10]];
console.log(arrays.reduce(function(a, b) {
return a.filter(function(value) {
return !b.includes(value);
});
}));
// output: [1, 3, 4]

// ES6
let arrays = [[1, 2, 3, 4, 5], [5, 2, 10]];
console.log(arrays.reduce((a, b) => a.filter(c => !b.includes(c))));
// output: [1, 3, 4]
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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$3

Creates a slice of array with n elements dropped from the beginning.

`js
// Underscore/Lodash
_.drop([1, 2, 3]);
// => [2, 3]

_.drop([1, 2, 3], 2);
// => [3]

// Native
[1, 2, 3].slice(1);
// => [2, 3]

[1, 2, 3].slice(2);
// => [3]
`

#### Browser Support for Array.prototype.slice()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

Creates a slice of array with n elements dropped at the end.

`js
// Underscore/Lodash
_.dropRight([1, 2, 3]);
// => [1, 2]

_.dropRight([1, 2, 3], 2);
// => [1]

// Native
[1, 2, 3].slice(0, -1);
// => [1, 2]

[1, 2, 3].slice(0, -2);
// => [1]
`

#### Browser Support for Array.prototype.slice()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

Fills elements of array with value from start up to, but not including, end.

> [!NOTE]
> fill is a mutable method in both native and Lodash/Underscore.

`js
// Underscore/Lodash
var array = [1, 2, 3]

_.fill(array, 'a')

console.log(array)
// output: ['a', 'a', 'a']

_.fill(Array(3), 2)
// output: [2, 2, 2]

_.fill([4, 6, 8, 10], '*', 1, 3)
// output: [4, '', '', 10]

// Native
var array = [1, 2, 3]

array.fill('a')

console.log(array)
// output: ['a', 'a', 'a']

Array(3).fill(2)
// output: [2, 2, 2]

[4, 6, 8, 10].fill('*', 1, 3)
// output: [4, '', '', 10]
`

#### Browser Support for Array.prototype.fill()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 31.0 ✔ | ✖ | 32.0 ✔ | 8 ✔ |

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$3

Returns the value of the first element in the array that satisfies the provided testing function. Otherwise undefined is returned.

`js
// Underscore/Lodash
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]

_.find(users, function (o) { return o.age < 40; })
// output: object for 'barney'

// Native
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]

users.find(function (o) { return o.age < 40; })
// output: object for 'barney'
`

#### Browser Support for Array.prototype.find()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 25.0 ✔ | ✖ | 32.0 ✔ | 7.1 ✔ |

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$3

Returns the index of the first element in the array that satisfies the provided testing function. Otherwise -1 is returned.

`js
// Underscore/Lodash
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]

var index = _.findIndex(users, function (o) { return o.age >= 40; })
console.log(index)
// output: 1

// Native
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
]

var index = users.findIndex(function (o) { return o.age >= 40; })
console.log(index)
// output: 1
`

#### Browser Support for Array.prototype.findIndex()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 25.0 ✔ | ✖ | 32.0 ✔ | 7.1 ✔ |

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$3

Returns the first element of an array. Passing n will return the first n elements of the array.

`js
// Underscore/Lodash
_.first([1, 2, 3, 4, 5]);
// => 1

// Underscore
_.first([1, 2, 3, 4, 5], 2);
// => [1, 2]

// Native
[1, 2, 3, 4, 5][0];
// => 1
//or
[].concat(1, 2, 3, 4, 5).shift()
// => 1
//or
[].concat([1, 2, 3, 4, 5]).shift()
// => 1

// Native (works even with potentially undefined/null, like _.first)
[].concat(undefined).shift()
// => undefined

[1, 2, 3, 4, 5].slice(0, 2);
// => [1, 2]

// Native with ES13
[1, 2, 3, 4, 5].at(0)
// => 1
//or
[].at(0)
// => undefined
`

#### Browser Support for Array.prototype.slice()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

#### Browser Support for Array.prototype.at()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
92 ✔ | 92 ✔ | 90 ✔ | ✖ | 78 ✔ | 15.4 ✔ |

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$3

Flattens array a single level deep.

`js
// Underscore/Lodash
_.flatten([1, [2, [3, [4]], 5]]);
// => [1, 2, [3, [4]], 5]

// Native
const flatten = [1, [2, [3, [4]], 5]].reduce( (a, b) => a.concat(b), [])
// => [1, 2, [3, [4]], 5]

const flatten = [].concat(...[1, [2, [3, [4]], 5]])
// => [1, 2, [3, [4]], 5]

// Native(ES2019)
const flatten = [1, [2, [3, [4]], 5]].flat()
// => [1, 2, [3, [4]], 5]

const flatten = [1, [2, [3, [4]], 5]].flatMap(number => number)
// => [1, 2, [3, [4]], 5]
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4 ✔ |

#### Browser Support for Array.prototype.flat()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |

#### Browser Support for Array.prototype.flatMap()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |

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$3

Recursively flattens array.

`js
// Underscore/Lodash
_.flattenDeep([1, [2, [3, [4]], 5]]);
// => [1, 2, 3, 4, 5]

// Native
const flattenDeep = (arr) => Array.isArray(arr)
? arr.reduce( (a, b) => a.concat(flattenDeep(b)) , [])
: [arr]

flattenDeep([1, [[2], [3, [4]], 5]])
// => [1, 2, 3, 4, 5]

// Native(ES2019)
[1, [2, [3, [4]], 5]].flat(Infinity)
// => [1, 2, 3, 4, 5]

const flattenDeep = (arr) => arr.flatMap((subArray, index) => Array.isArray(subArray) ? flattenDeep(subArray) : subArray)

flattenDeep([1, [[2], [3, [4]], 5]])
// => [1, 2, 3, 4, 5]
`

#### Browser Support

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 7.1 ✔ |


#### Browser Support for Array.prototype.flat()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |


#### Browser Support for Array.prototype.flatMap()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |


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$3

Returns an object composed from key-value pairs.

`js
// Underscore/Lodash
_.fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

// Native
const fromPairs = function(arr) {
return arr.reduce(function(accumulator, value) {
accumulator[value[0]] = value[1];
return accumulator;
}, {})
}

// Compact form
const fromPairs = (arr) => arr.reduce((acc, val) => (acc[val[0]] = val[1], acc), {})

fromPairs([['a', 1], ['b', 2]]);
// => { 'a': 1, 'b': 2 }

// Native(ES2019)
Object.fromEntries([['a', 1], ['b', 2]])
// => { 'a': 1, 'b': 2 }
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

#### Browser Support for Object.fromEntries()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
73.0 ✔ | 79.0 ✔ | 63.0 ✔ | ✖ | 60 ✔ | 12.1 ✔ |

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$3

Gets the first element or all but the first element.

`js
const array = [1, 2, 3]

// Underscore: _.first, _.head, _.take
// Lodash: _.first, _.head
_.head(array)
// output: 1

// Underscore: _.rest, _.tail, _.drop
// Lodash: _.tail
_.tail(array)
// output: [2, 3]


// Native
const [ head, ...tail ] = array
console.log(head)
// output: 1
console.log(tail)
// output [2, 3]

// Native replacement for _.head in ES13
array.at(0)
// output: 1
`

#### Browser Support for Spread in array literals

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |

#### Browser Support for Array.prototype.at()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
92 ✔ | 92 ✔ | 90 ✔ | ✖ | 78 ✔ | 15.4 ✔ |

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$3

Returns the first index at which a given element can be found in the array, or -1 if it is not present.

`js
// Underscore/Lodash
var array = [2, 9, 9]
var result = _.indexOf(array, 2)
console.log(result)
// output: 0

// Native
var array = [2, 9, 9]
var result = array.indexOf(2)
console.log(result)
// output: 0
`

#### Browser Support for Array.prototype.indexOf()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

Returns an array that is the intersection of all the arrays. Each value in the result is present in each of the arrays.

`js
// Underscore/Lodash
console.log(_.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]))
// output: [1, 2]

// Native
var arrays = [[1, 2, 3], [101, 2, 1, 10], [2, 1]];
console.log(arrays.reduce(function(a, b) {
return a.filter(function(value) {
return b.includes(value);
});
}));
// output: [1, 2]

// ES6
let arrays = [[1, 2, 3], [101, 2, 1, 10], [2, 1]];
console.log(arrays.reduce((a, b) => a.filter(c => b.includes(c))));
// output: [1, 2]
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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$3

Creates a slice of array with n elements taken from the end.

> [!IMPORTANT]
> Native slice does not behave entirely the same as the Lodash method. See example below to understand why.

`js
// Underscore/Lodash
_.takeRight([1, 2, 3]);
// => [3]

_.takeRight([1, 2, 3], 2);
// => [2, 3]

_.takeRight([1, 2, 3], 5);
// => [1, 2, 3]

// Native
[1, 2, 3].slice(-1);
// => [3]

[1, 2, 3].slice(-2);
// => [2, 3]

[1, 2, 3].slice(-5);
// => [1, 2, 3]

// Difference in compatibility

// Lodash
_.takeRight([1, 2, 3], 0);
// => []

// Native
[1, 2, 3].slice(0);
// => [1, 2, 3]
`

#### Browser Support for Array.prototype.slice()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

Returns true if given value is an array.

`js
// Lodash
var array = []
console.log(_.isArray(array))
// output: true

// Native
var array = []
console.log(Array.isArray(array));
// output: true
`

#### Browser Support for Array.isArray()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |

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$3

Checks if value is classified as an ArrayBuffer object.

`js
// Lodash
_.isArrayBuffer(new ArrayBuffer(2));
// output: true

// Native
console.log(new ArrayBuffer(2) instanceof ArrayBuffer);
// output: true
`

> [!WARNING]
> You will get the wrong result if you get ArrayBuffer from another realm.
> See details.

#### Browser Support for instanceof

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

> [!IMPORTANT]
> Not in Underscore.js

Joins a list of elements in an array with a given separator.

`js
// Lodash
var result = _.join(['one', 'two', 'three'], '--')
console.log(result)
// output: 'one--two--three'

// Native
var result = ['one', 'two', 'three'].join('--')
console.log(result)
// output: 'one--two--three'
`

#### Browser Support for Array.prototype.join()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |

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$3

Returns the last element of an array. Passing n will return the last n elements of the array.

`js
// Underscore/Lodash
const numbers = [1, 2, 3, 4, 5];
_.last(numbers);
// => 5

// Underscore
_.last(numbers, 2);
// => [4, 5]

// Native
const numbers = [1, 2, 3, 4, 5];
numbers[numbers.length - 1];
// => 5
//or
numbers.slice(-1)[0];
// => 5
//or
[].concat(numbers).pop()
// => 5
//or
numbers.at(-1);
// => 5

// Native (works even with potentially undefined/null)
[].concat(undefined).pop()
// => undefined

numbers.slice(-2);
// => [4, 5]
`

#### Browser Support for Array.prototype.concat()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |

#### Browser Support for Array.prototype.at()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
92 ✔ | 92 ✔ | 90 ✔ | ✖ | 78 ✔ | 15.4 ✔ |

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$3

Returns the index of the last occurrence of value in the array, or -1 if value is not present.

`js
// Underscore/Lodash
var array = [2, 9, 9, 4, 3, 6]
var result = _.lastIndexOf(array, 9)
console.log(result)
// output: 2

// Native
var array = [2, 9, 9, 4, 3, 6]
var result = array.lastIndexOf(9)
console.log(result)
// output: 2
`

#### Browser Support for Array.prototype.lastIndexOf()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

> [!IMPORTANT]
> Not in Underscore.js

Reverses array so that the first element becomes the last, the second element becomes the second to last, and so on.

`js
// Lodash
var array = [1, 2, 3]
console.log(_.reverse(array))
// output: [3, 2, 1]

// Native
var array = [1, 2, 3]
console.log(array.reverse())
// output: [3, 2, 1]
`

Voice from the Lodash author:

> Lodash's _.reverse just calls Array#reverse and enables composition like _.map(arrays, _.reverse).
> It's exposed on _ because previously, like Underscore, it was only exposed in the chaining syntax.
> --- jdalton

#### Browser Support for Array.prototype.reverse()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |

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$3

Returns a shallow copy of a portion of an array into a new array object selected from begin to end (end not included)

`js
// Lodash
var array = [1, 2, 3, 4]
console.log(_.slice(array, 1, 3))
// output: [2, 3]

// Native
var array = [1, 2, 3, 4]
console.log(array.slice(1, 3));
// output: [2, 3]
`

#### Browser Support for Array.prototype.slice()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

> [!IMPORTANT]
> Not in Underscore.js

Returns an array where matching items are filtered.

`js
// Lodash
var array = [1, 2, 3]
console.log(_.without(array, 2))
// output: [1, 3]

// Native
var array = [1, 2, 3]
console.log(array.filter(function(value) {
return value !== 2;
}));
// output: [1, 3]
`

#### Browser Support for Array.prototype.filter()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |

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$3

Returns everything but the last entry of the array. Pass n to exclude the last n elements from the result.

`js
// Underscore
var array = [5, 4, 3, 2, 1]
console.log(_.initial(array, 2))
// output: [5, 4, 3]

// Native
var array = [5, 4, 3, 2, 1]
console.log(array.slice(0, -2));
// output: [5, 4, 3]
`

#### Browser Support for Array.prototype.slice()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

Removes all provided values from the given array using strict equality for comparisons, i.e. ===.

`js
// Lodash
const array = [1, 2, 3, 1, 2, 3];
_.pull(array, 2, 3);
console.log(array); // output: [1, 1]
`

`js
// Native JS
const array = [1, 2, 3, 1, 2, 3];
function pull(arr, ...removeList){
var removeSet = new Set(removeList)
return arr.filter(function(el){
return !removeSet.has(el)
})
}
console.log(pull(array, 2, 3)); // output: [1, 1]
console.log(array); // still [1, 2, 3, 1, 2, 3]. This is not in place, unlike lodash!
`

`ts
// TypeScript
const array = [1, 2, 3, 1, 2, 3];
const pull = (sourceArray: T[], ...removeList: T[]): T[] => {
const removeSet = new Set(removeList);
return sourceArray.filter(el => !removeSet.has(el));
};
console.log(pull(array, 2, 3)); // output: [1, 1]
console.log(array); // still [1, 2, 3, 1, 2, 3]. This is not in place, unlike lodash!
`

#### Browser Support for Array.prototype.filter()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |

#### Browser Support for Set.prototype.has()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
38 ✔ | 12 ✔ | 13 ✔ | 11 ✔ | 25 ✔ | 8 ✔ |

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$3

Creates an array of unique values, taking an iteratee to compute uniqueness with
(note that to iterate by a key in an object you must use x => x.key instead of key for the iteratee)

`js
// Lodash
var array1 = [2.1];
var array2 = [1.2, 2.3];
var result = _.unionBy(array1, array2, Math.floor)
console.log(result)
// output: [2.1, 1.2]

// Native
var array1 = [2.1];
var array2 = [1.2, 2.3];
function unionBy(...arrays) {
const iteratee = (arrays).pop();

if (Array.isArray(iteratee)) {
return []; // return empty if iteratee is missing
}

return [...arrays].flat().filter(
(set => (o) => set.has(iteratee(o)) ? false : set.add(iteratee(o)))(new Set()),
);
};
console.log(unionBy(array1, array2, Math.floor))
// output: [2.1, 1.2]
`

#### Browser Support for Array.prototype.flat()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
69 ✔ | 79 ✔ | 62 ✔ | ✖ | 56 ✔ | 12 ✔ |

#### Browser Support for Array.isArray()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |

#### Browser Support for Set.prototype.has()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image] |
:-: | :-: | :-: | :-: | :-: | :-: |
38 ✔ | 12 ✔ | 13 ✔ | 11 ✔ | 25 ✔ | 8 ✔ |

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Collection*

> [!IMPORTANT]
> Most native equivalents are array methods,
> and will not work with objects. If this functionality is needed and no object method is provided,
> then Lodash/Underscore is the better option.

$3

Iterates over a list of elements, yielding each in turn to an iteratee function.

`js
// Underscore/Lodash
//For arrays
_.each([1, 2, 3], function (value, index) {
console.log(value)
})
// output: 1 2 3

//For objects
_.each({'one':1, 'two':2, 'three':3}, function(value) {
console.log(value)
})
// output: 1 2 3

// Native
//For arrays
[1, 2, 3].forEach(function (value, index) {
console.log(value)
})
// output: 1 2 3

//For objects
Object.entries({'one':1, 'two':2, 'three':3}).forEach(function([key,value],index) {
console.log(value)
})
//output: 1 2 3
`

#### Browser Support for Array.prototype.forEach()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

#### Browser Support for Object.entries().forEach()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
54 ✔ | 14 ✔ | 47 ✔ | ✖ | 41 ✔ | 10.1✔ |

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$3

Tests whether all elements in the array pass the test implemented by the provided function.

`js
// Underscore/Lodash
function isLargerThanTen (element, index, array) {
return element >= 10
}
var array = [10, 20, 30]
var result = _.every(array, isLargerThanTen)
console.log(result)
// output: true

// Native
function isLargerThanTen (element, index, array) {
return element >= 10
}

var array = [10, 20, 30]
var result = array.every(isLargerThanTen)
console.log(result)
// output: true
`

#### Browser Support for Array.prototype.every()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

Creates a new array with all elements that pass the test implemented by the provided function.

`js
// Underscore/Lodash
function isBigEnough (value) {
return value >= 10
}
var array = [12, 5, 8, 130, 44]
var filtered = _.filter(array, isBigEnough)
console.log(filtered)
// output: [12, 130, 44]

// Native
function isBigEnough (value) {
return value >= 10
}
var array = [12, 5, 8, 130, 44]
var filtered = array.filter(isBigEnough)
console.log(filtered)
// output: [12, 130, 44]
`

#### Browser Support for Array.prototype.filter()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9 ✔ | ✔ | ✔ |

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$3

Group items by key.

`js
// Underscore/Lodash
var grouped = _.groupBy(['one', 'two', 'three'], 'length')
console.log(grouped)
// output: {3: ["one", "two"], 5: ["three"]}

// Native
var grouped = ['one', 'two', 'three'].reduce((r, v, i, a, k = v.length) => ((r[k] || (r[k] = [])).push(v), r), {})
console.log(grouped)
// output: {3: ["one", "two"], 5: ["three"]}

// Native
Object.groupBy(['one', 'two', 'three'], ({length}) => length)
// output: {3: ["one", "two"], 5: ["three"]}
`

`js
// Underscore/Lodash
var grouped = _.groupBy([1.3, 2.1, 2.4], num => Math.floor(num))
console.log(grouped)
// output: {1: [1.3], 2: [2.1, 2.4]}

// Native
var grouped = [1.3, 2.1, 2.4].reduce((r, v, i, a, k = Math.floor(v)) => ((r[k] || (r[k] = [])).push(v), r), {})
console.log(grouped)
// output: {1: [1.3], 2: [2.1, 2.4]}

// Native
Object.groupBy([1.3, 2.1, 2.4], num => Math.floor(num))
// output: {1: [1.3], 2: [2.1, 2.4]}
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

#### Browser Support for Object.groupBy()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
117.0 ✔ | 117.0 ✔ | 119.0 ✔ | ✖ | 103.0 ✔ | 16.4 ✔ |

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$3

Checks if a value is in collection.

`js
var array = [1, 2, 3]
// Underscore/Lodash - also called _.contains
_.includes(array, 1)
// output: true

// Native
var array = [1, 2, 3]
array.includes(1)
// output: true

// Native (does not use same value zero)
var array = [1, 2, 3]
array.indexOf(1) > -1
// output: true
`

#### Browser Support for Array.prototype.includes

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
47.0 ✔ | 14.0 ✔ | 43.0 ✔ | ✖ | 34.0 ✔ | 9.0 ✔ |

#### Browser Support for Array.prototype.indexOf

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

> [!WARNING]
> Not in Underscore.js

Creates an object composed of keys generated from the results of running each element of collection through iteratee.

`js
// Lodash
console.log(_.keyBy(['a', 'b', 'c']))
// output: { a: 'a', b: 'b', c: 'c' }
console.log(_.keyBy([{ id: 'a1', title: 'abc' }, { id: 'b2', title: 'def' }], 'id'))
// output: { a1: { id: 'a1', title: 'abc' }, b2: { id: 'b2', title: 'def' } }
console.log(_.keyBy({ data: { id: 'a1', title: 'abc' }}, 'id'))
// output: { a1: { id: 'a1', title: 'abc' }}

// keyBy for array only
const keyBy = (array, key) => (array || []).reduce((r, x) => ({ ...r, [key ? x[key] : x]: x }), {});

// Native
console.log(keyBy(['a', 'b', 'c']))
// output: { a: 'a', b: 'b', c: 'c' }
console.log(keyBy([{ id: 'a1', title: 'abc' }, { id: 'b2', title: 'def' }], 'id'))
// output: { a1: { id: 'a1', title: 'abc' }, b2: { id: 'b2', title: 'def' } }
console.log(keyBy(Object.values({ data: { id: 'a1', title: 'abc' }}), 'id'))
// output: { a1: { id: 'a1', title: 'abc' }}

// keyBy for array and object
const collectionKeyBy = (collection, key) => {
const c = collection || {};
return c.isArray() ? keyBy(c, key) : keyBy(Object.values(c), key);
}
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | 12.0 ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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$3

Translates all items in an array or object to new array of items.

`js
// Underscore/Lodash
var array1 = [1, 2, 3]
var array2 = _.map(array1, function (value, index) {
return value * 2
})
console.log(array2)
// output: [2, 4, 6]

// Native
var array1 = [1, 2, 3]
var array2 = array1.map(function (value, index) {
return value * 2
})
console.log(array2)
// output: [2, 4, 6]
`

`js
// Underscore/Lodash
var object1 = { 'a': 1, 'b': 2, 'c': 3 }
var object2 = _.map(object1, function (value, index) {
return value * 2
})
console.log(object2)
// output: [2, 4, 6]

// Native
var object1 = { 'a': 1, 'b': 2, 'c': 3 }
var object2 = Object.entries(object1).map(function ([key, value], index) {
return value * 2
})
console.log(object2)
// output: [2, 4, 6]
`

#### Browser Support for Object.entries() and destructuring

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | ✖ | ✔ | ✔ |

#### Browser Support for Array.prototype.map()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

Use Array.prototype.reduce() for find the maximum or minimum collection item

`js
// Underscore/Lodash
var data = [{ value: 6 }, { value: 2 }, { value: 4 }]
var minItem = _.minBy(data, 'value')
var maxItem = _.maxBy(data, 'value')
console.log(minItem, maxItem)
// output: { value: 2 } { value: 6 }

// Native
var data = [{ value: 6 }, { value: 2 }, { value: 4 }]
var minItem = data.reduce(function(a, b) { return a.value <= b.value ? a : b }, {})
var maxItem = data.reduce(function(a, b) { return a.value >= b.value ? a : b }, {})
console.log(minItem, maxItem)
// output: { value: 2 }, { value: 6 }
`

Extract a functor and use es2015 for better code

`js
// utils
const makeSelect = (comparator) => (a, b) => comparator(a, b) ? a : b
const minByValue = makeSelect((a, b) => a.value <= b.value)
const maxByValue = makeSelect((a, b) => a.value >= b.value)

// main logic
const data = [{ value: 6 }, { value: 2 }, { value: 4 }]
const minItem = data.reduce(minByValue, {})
const maxItem = data.reduce(maxByValue, {})

console.log(minItem, maxItem)
// output: { value: 2 }, { value: 6 }

// or also more universal and little slower variant of minBy
const minBy = (collection, key) => {
// slower because need to create a lambda function for each call...
const select = (a, b) => a[key] <= b[key] ? a : b
return collection.reduce(select, {})
}

console.log(minBy(data, 'value'))
// output: { value: 2 }
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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$3

array.map or _.map can also be used to replace _.pluck.
Lodash v4.0 removed _.pluck in favor of _.map with iteratee shorthand.
Details can be found in Changelog

`js
// Underscore/Lodash
var array1 = [{name: "Alice"}, {name: "Bob"}, {name: "Jeremy"}]
var names = _.pluck(array1, "name")
console.log(names)
// output: ["Alice", "Bob", "Jeremy"]

// Native
var array1 = [{name: "Alice"}, {name: "Bob"}, {name: "Jeremy"}]
var names = array1.map(function(x){
return x.name
})
console.log(names)
// output: ["Alice", "Bob", "Jeremy"]
`

#### Browser Support for Array.prototype.map()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

Applies a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.

`js
// Underscore/Lodash
var array = [0, 1, 2, 3, 4]
var result = _.reduce(array, function (previousValue, currentValue, currentIndex, array) {
return previousValue + currentValue
})
console.log(result)
// output: 10

// Native
var array = [0, 1, 2, 3, 4]
var result = array.reduce(function (previousValue, currentValue, currentIndex, array) {
return previousValue + currentValue
})
console.log(result)
// output: 10
`

#### Browser Support for Array.prototype.reduce()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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$3

Creates an array of numbers progressing from start up to.

`js
// Underscore/Lodash
_.range(4) // output: [0, 1, 2, 3]
_.range(-4) // output: [0, -1, -2, -3]
_.range(1, 5) // output: [1, 2, 3, 4]
_.range(0, 20, 5) // output: [0, 5, 10, 15]

// Native ( solution with Array.from )
Array.from({length: 4}, (_, i) => i) // output: [0, 1, 2, 3]
Array.from({length: 4}, (_, i) => -i) // output: [-0, -1, -2, -3]
Array.from({length: 4}, (_, i) => i + 1) // output: [1, 2, 3, 4]
Array.from({length: 4}, (_, i) => i * 5) // output: [0, 5, 10, 15]

// Native ( solution with keys() and spread )
[...Array(4).keys()] // output: [0, 1, 2, 3]
[...Array(4).keys()].map(k => -k) // output: [-0, -1, -2, -3]
[...Array(4).keys()].map(k => k + 1) // output: [1, 2, 3, 4]
[...Array(4).keys()].map(k => k * 5) // output: [0, 5, 10, 15]
`


#### Browser Support for Array.from()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
45.0 ✔ | ✔ | 32.0 ✔ | ✖ | ✔ | 9.0 ✔ |

#### Browser Support for keys and spread in Array literals

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 7.1 ✔ |

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$3

This method is like _.reduce except that it iterates over elements of collection from right to left.

`js
// Underscore/Lodash
var array = [0, 1, 2, 3, 4]
var result = _.reduceRight(array, function (previousValue, currentValue, currentIndex, array) {
return previousValue - currentValue
})
console.log(result)
// output: -2

// Native
var array = [0, 1, 2, 3, 4]
var result = array.reduceRight(function (previousValue, currentValue, currentIndex, array) {
return previousValue - currentValue
})
console.log(result)
// output: -2
`

#### Browser Support for Array.prototype.reduceRight()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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$3

The opposite of _.filter; this method returns the elements of collection that predicate does not return truthy for.

`js
// Underscore/Lodash
var array = [1, 2, 3, 4, 5];
var result = _.reject(array, function (x) {
return x % 2 === 0;
});
// output: [1, 3, 5]

// Native
var array = [1, 2, 3, 4, 5];

var reject = function (arr, predicate) {
var complement = function (f) {
return function (x) {
return !f(x);
}
};

return arr.filter(complement(predicate));
};
// output: [1, 3, 5]
`

#### Browser Support for Array.prototype.filter()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | 12 ✔ | 1.5 ✔ | 9.0 ✔ | 9.5 ✔ | 3.0 ✔ |

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$3

Gets a random element from array.

`js
// Underscore/Lodash
const array = [0, 1, 2, 3, 4]
const result = _.sample(array)
console.log(result)
// output: 2

// Native
const array = [0, 1, 2, 3, 4]
const sample = arr => {
const len = arr == null ? 0 : arr.length
return len ? arr[Math.floor(Math.random() * len)] : undefined
}

const result = sample(array)
console.log(result)
// output: 2
`

#### Browser Support for Array.prototype.length() and Math.random()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.0 ✔ | ✔ | ✔ | ✔ |

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$3

Returns the number of values in the collection.

`js
// Underscore/Lodash
var result = _.size({one: 1, two: 2, three: 3})
console.log(result)
// output: 3

// Native
var result2 = Object.keys({one: 1, two: 2, three: 3}).length
console.log(result2)
// output: 3
`

#### Browser Support for Object.keys()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 12.0 ✔ | 5.0 ✔ |

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$3

Tests whether any of the elements in the array pass the test implemented by the provided function.

`js
// Underscore/Lodash
function isLargerThanTen (element, index, array) {
return element >= 10
}
var array = [10, 9, 8]
var result = _.some(array, isLargerThanTen)
console.log(result)
// output: true

// Native
function isLargerThanTen (element, index, array) {
return element >= 10
}

var array = [10, 9, 8]
var result = array.some(isLargerThanTen)
console.log(result)
// output: true
`

#### Browser Support for Array.prototype.some()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | ✔ 9.0 | ✔ | ✔ |

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$3

Sorts an array of object based on an object key provided by a parameter (note this is more limited than Underscore/Lodash).

`js
const fruits = [
{name:"banana", amount: 2},
{name:"apple", amount: 4},
{name:"pineapple", amount: 2},
{name:"mango", amount: 1}
];

// Underscore
_.sortBy(fruits, 'name');
// => [{name:"apple", amount: 4}, {name:"banana", amount: 2}, {name:"mango", amount: 1}, {name:"pineapple", amount: 2}]

// Lodash
_.orderBy(fruits, ['name'],['asc']);
// => [{name:"apple", amount: 4}, {name:"banana", amount: 2}, {name:"mango", amount: 1}, {name:"pineapple", amount: 2}]

// Native
const sortBy = (key) => {
return (a, b) => (a[key] > b[key]) ? 1 : ((b[key] > a[key]) ? -1 : 0);
};

// The native sort modifies the array in place. _.orderBy and _.sortBy do not, so we use .concat() to
// copy the array, then sort.
fruits.concat().sort(sortBy("name"));
// => [{name:"apple", amount: 4}, {name:"banana", amount: 2}, {name:"mango", amount: 1}, {name:"pineapple", amount: 2}]
`

#### Browser Support for Array.prototype.concat() and Array.prototype.sort()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
1.0 ✔ | ✔ | 1.0 ✔ | 5.5 ✔ | ✔ | ✔ |

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$3

Produces a duplicate-free version of the array, using === to test object equality.

`js
// Underscore/Lodash
var array = [1, 2, 1, 4, 1, 3]
var result = _.uniq(array)
console.log(result)
// output: [1, 2, 4, 3]

// Native
var array = [1, 2, 1, 4, 1, 3];
var result = [...new Set(array)];
console.log(result)
// output: [1, 2, 4, 3]
`

#### Browser Support for Spread in array literals

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |

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Function

$3

> [!WARNING]
> This is an alternative implementation

Creates a version of the function that will only be run after first being called count times. Useful for grouping asynchronous responses, where you want to be sure that all the async calls have finished, before proceeding.

`js
var notes = ['profile', 'settings']
// Underscore/Lodash
var renderNotes = _.after(notes.length, render)
notes.forEach(function (note) {
console.log(note)
renderNotes()
})

// Native
notes.forEach(function (note, index) {
console.log(note)
if (notes.length === (index + 1)) {
render()
}
})
`

#### Browser Support for Array.prototype.forEach()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | 1.5 ✔ | 9.0 ✔ | ✔ | ✔ |

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$3

Create a new function that calls _func_ with _thisArg_ and _args_.

`js
var objA = {
x: 66,
offsetX: function(offset) {
return this.x + offset;
}
}

var objB = {
x: 67
};

// Underscore/Lodash
var boundOffsetX = _.bind(objA.offsetX, objB, 0);

// Native
var boundOffsetX = objA.offsetX.bind(objB, 0);
`

#### Browser Support for Function.prototype.bind()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
7.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 11.6 ✔ | 5.1 ✔ |

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$3

Checks if value is classified as a _Function_ object.

`js
// Lodash
_.isFunction(console.log);
// => true

_.isFunction(/abc/);
// => false

// Native
function isFunction(func) {
return typeof func === "function";
}

isFunction(setTimeout);
// => true

isFunction(123);
// => false
`

#### Browser Support

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |

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$3

Create a new function that calls func with thisArg and args.

`js
function debounce(func, wait, immediate) {
var timeout;
return function() {
var context = this, args = arguments;
clearTimeout(timeout);
if (immediate && !timeout) func.apply(context, args);
timeout = setTimeout(function() {
timeout = null;
if (!immediate) func.apply(context, args);
}, wait);
};
}

// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', debounce(calculateLayout, 150));
`

#### Browser Support for debounce

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
7.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 11.6 ✔ | 5.1 ✔ |

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$3

Create a new function that calls func with args.

`js
// Lodash
function greet(greeting, name) {
return greeting + ' ' + name;
}
var sayHelloTo = _.partial(greet, 'Hello');
var result = sayHelloTo('Jose')
console.log(result)
// output: 'Hello Jose'

// Native
function greet(greeting, name) {
return greeting + ' ' + name;
}
var sayHelloTo = (...args) => greet('Hello', ...args)
var result = sayHelloTo('Jose')
console.log(result)
// output: 'Hello Jose'

// Native
const partial = (func, ...boundArgs) => (...remainingArgs) => func(...boundArgs, ...remainingArgs)
var sayHelloTo = partial(greet, 'Hello');
var result = sayHelloTo('Jose')
console.log(result)
// output: 'Hello Jose'
`

#### Browser Support for Spread

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
46.0 ✔ | 12.0 ✔ | 16.0 ✔ | ✖ | 37.0 ✔ | 8.0 ✔ |

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$3

Create a new function that limits calls to func to once every given timeframe.

`js
function throttle(func, timeFrame) {
var lastTime = 0;
return function (...args) {
var now = new Date();
if (now - lastTime >= timeFrame) {
func(...args);
lastTime = now;
}
};
}

// Avoid running the same function twice within the specified timeframe.
jQuery(window).on('resize', throttle(calculateLayout, 150));
`

#### Browser Support for throttle

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | 12.0 ✔ | 3.0 ✔ | 9.0 ✔ | 10.5 ✔ | 4.0 ✔ |

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Lang

$3

Puts the value into an array of length one if it is not already an array.

`js
// Underscore
console.log(_.castArray(5))
// output: [5]
console.log(_.castArray([2]))
// output: [2]

// Native
function castArray(arr) {
return Array.isArray(arr) ? arr : [arr]
}
// output: true
console.log(castArray(5));
// output: [5]
console.log(castArray([2]));
// output: [2]
`

#### Browser Support for Array.isArray()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
5.0 ✔ | ✔ | 4.0 ✔ | 9.0 ✔ | 10.5 ✔ | 5.0 ✔ |

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$3

Creates a deep copy by recursively cloning the value.

`js
// Lodash
var objects = [{ 'a': 1 }, { 'b': 2 }];

var clone = _.cloneDeep(objects);
console.log(clone[0] === objects[0]);
// output: false

// Native
var objects = [{ 'a': 1 }, { 'b': 2 }];

var clone = structuredClone(objects);
console.log(clone[0] === objects[0]);
// output: false
`

#### Browser Support for structuredClone()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
98.0 ✔ | 98.0 ✔ | 94.0 ✔ | ✖ | 84.0 ✔ | 15.4 ✔ |

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$3

Checks if value is classified as a Date object.

`js
// Lodash
console.log(_.isDate(new Date));
// output: true

// Native
console.log(Object.prototype.toString.call(new Date) === "[object Date]");
// output: true
`

#### Browser Support for String.prototype.toString.call()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |

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$3

Checks if value is greater than other.

`js
// Lodash
console.log(_.gt(3, 1))
// output: true

// Native
console.log(3 > 1);
// output: true
`

#### Browser Support

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |

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$3

Checks if value is greater than or equal to other.

`js
// Lodash
console.log(_.gte(3, 1))
// output: true

// Native
console.log(3 >= 1);
// output: true
`

#### Browser Support

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
✔ | ✔ | ✔ | ✔ | ✔ | ✔ |

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$3

Checks if value is an empty object or collection.

> [!WARNING]
> The Native version does not support evaluating a Set or a Map

`js
// Lodash
console.log(_.isEmpty(null))
// output: true
console.log(_.isEmpty(''))
// output: true
console.log(_.isEmpty({}))
// output: true
console.log(_.isEmpty([]))
// output: true
console.log(_.isEmpty({a: '1'}))
// output: false

// Native
const isEmpty = obj => [Object, Array].includes((obj || {}).constructor) && !Object.entries((obj || {})).length;

console.log(isEmpty(null))
// output: true
console.log(isEmpty(''))
// output: true
console.log(isEmpty({}))
// output: true
console.log(isEmpty([]))
// output: true
console.log(isEmpty({a: '1'}))
// output: false
`

#### Browser Support for Array.prototype.includes()

![Chrome][chrome-image] | ![Edge][edge-image] | ![Firefox][firefox-image] | ![IE][ie-image] | ![Opera][opera-image] | ![Safari][safari-image]
:-: | :-: | :-: | :-: | :-: | :-: |
47.0 ✔ | 14.0 ✔ | 43.0 ✔ | ✖ | 34.0 ✔ | 9.0 ✔ |

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$3

Checks if value is a finite primitive number.

`js
// Lodash
console.log(_.isFinite('3'))
// output: false
console.log(_.isFinite(3))
// output: true

// Native
console.log(Number.isFinite('3'))
// output: false
console.log(Number.isFinite(3))
// output: true
`

#### Browser Support for Number.isFinite()`

![Chrome][chrome-image] | ![E