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;

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, you can also call fyMap with an alternate syntax;

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.

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.