https://github.com/ticky/fisher-yates-map
🎲 A map implementation which calls the callback for each element in a random order
https://github.com/ticky/fisher-yates-map
fisher-yates fisher-yates-map map
Last synced: 4 months ago
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🎲 A map implementation which calls the callback for each element in a random order
- Host: GitHub
- URL: https://github.com/ticky/fisher-yates-map
- Owner: ticky
- License: mit
- Created: 2017-06-16T23:08:50.000Z (about 9 years ago)
- Default Branch: develop
- Last Pushed: 2026-03-01T17:46:47.000Z (4 months ago)
- Last Synced: 2026-03-01T19:49:22.480Z (4 months ago)
- Topics: fisher-yates, fisher-yates-map, map
- Language: JavaScript
- Homepage:
- Size: 349 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 18
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# Fisher-Yates Map
[](https://www.npmjs.com/package/fisher-yates-map)  [](https://travis-ci.org/ticky/fisher-yates-map) [](https://codecov.io/gh/ticky/fisher-yates-map)
A map implementation which calls the callback for each element in a random order
## Usage
`fyMap` is a simple map function which accepts an array and a callback;
```js
import fyMap from 'fisher-yates-map';
const myArray = ['meow', 'purr', 'nya'];
const output = fyMap(myArray, (item, index, array) => {
console.log(`cat ${index + 1} ${item}s!`);
return `${item}~!`;
});
// => 'cat 2 purrs!'
// => 'cat 1 meows!'
// => 'cat 3 nyas!'
console.log(output);
// => ['meow~!', 'purr~!', 'nya~!']
```
The output will be the same as calling the equivalent built-in `Array.prototype.map` method, however, each item will be sent to the callback in a random order.
### With Babel Function Bind
If you're using [`babel-plugin-transform-function-bind`](http://babeljs.io/docs/plugins/transform-function-bind/), you can also call `fyMap` with an alternate syntax;
```js
const output = myArray::fyMap((item, index, array) => {
console.log(`cat ${index + 1} ${item}s!`);
return `${item}~!`;
});
```
More information about this syntax extension can be found [on Babel's website](http://babeljs.io/docs/plugins/transform-function-bind/).
## Why?
This could be useful in situations where the order of operations doesn't matter, or you want to enforce that per-item operations not rely on prior results. It could also be useful if you have a large number of operations which you'd like to scatter the application of.
## Caveats
`fyMap` doesn't implement the standard `Array.prototype.map` handling of `this`. If that doesn't work for you, you should probably use something else!
Performance is also imperfect - if you need something as fast as `Array.prototype.map` or a traditional loop, this isn't it.