jonschlinkert / array-last

Return the last element in an array. Faster than `.slice`

array-last

Get the last or last n elements in an array.

Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.

Install

Install with npm:

$ npm install --save array-last

Usage

var last = require('array-last');

last(['a', 'b', 'c', 'd', 'e', 'f']);
//=> 'f'

last(['a', 'b', 'c', 'd', 'e', 'f'], 1);
//=> 'f'

last(['a', 'b', 'c', 'd', 'e', 'f'], 3);
//=> ['d', 'e', 'f']

About

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Running Tests

Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:

$ npm install && npm test

Building docs

(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

To generate the readme, run the following command:

$ npm install -g verbose/verb#dev verb-generate-readme && verb

Related projects

You might also be interested in these projects:

• arr-union: Combines a list of arrays, returning a single array with unique values, using strict equality… more | homepage
• array-unique: Remove duplicate values from an array. Fastest ES5 implementation. | homepage
• array-xor: Returns the symmetric difference (exclusive-or) of an array of elements (elements that are present in… more | homepage

Contributors

Commits	Contributor
19	jonschlinkert
3	SpyMaster356
2	bendrucker
2	phated

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright © 2017, Jon Schlinkert. Released under the MIT License.

---

This file was generated by verb-generate-readme, v0.6.0, on November 30, 2017.

array-last's Issues

what if use Array.slice() directly?

//  Get the last or last n elements in an array.

export default function (array, num = 1) {
  if (!Array.isArray)
    throw new Error('array-first expects an array as the first element');

  if (typeof num !== 'number') throw new Error('num expects a number');

  if (array.length === 0) return null;

  return num === 1 ? array.pop() : array.slice(-num);
}

why don`t judge the length of the second parameters

When the length of the second parameters is greater than the length of the array，The undefined will be included in the result.

example:

 var last = require('array-last');

 var a = last(['a', 'b', 'c', 'd', 'e', 'f'],7);

result

[ undefined, 'a', 'b', 'c', 'd', 'e', 'f' ]

Why not use faster method?

function(ar) {
  return ar[ar.length-1];
}

The second argument maybe less than 0

Whe the second argument less than 0, there will be an error.
Should we change the code like below to support negative number.

example:

 n = isNumber(n) ? Math.abs(+n) : 1;

Benchmarked is not work

• Environment 1:
  • Arch linux/4.12.8-2-ARCH
  • node v8.5.0
  • npm 5.3.0
• Environment 2:
  • macOS 10.12.6
  • node v8.3.0
  • npm 5.4.2

$ npm list --depth=0
[email protected]
├── [email protected]
├── [email protected]
├── [email protected]
├── [email protected]
├── [email protected]
├── [email protected]
└── [email protected]

$ node benchmark
Benchmarking: (5 of 5)
 · 10
 · 1000
 · 100000
 · 1000000
 · 200

When I run node benchmark, I got 10, 1000, 100000, 1000000 and then nothing. benchmarked works well in is-number and kind-of, but not this repo. I have tried [email protected] & [email protected] on this, but it still the same, no errors & no more outputs.

what if second_params is greater than first_params.lenth?

you took independent action for scene -- n === 1, but another scene like n > arr.length , like arr.length == 1,
and its necessary to use another tool like is_number?
n = isNumber(n) ? +n :1; => n = typeof n == 'number' ? +n : 1;

add
if (n >= len || len == 1){ return arr }