Array.prototype.chunk: Splits an array into an array of smaller arrays containing `groupsize` members

array.chunk.js

/* 
Split an array into chunks and return an array
of these chunks.

With kudos to github.com/JudeQuintana

This is an update example for code I originally wrote 5+ years ago before
JavaScript took over the world.

Extending native objects like this is now considered a bad practice, so use
the stuff between the curly braces and create your own function instead.

*/

Array.prototype.chunk = function(groupsize){
    var sets = [], chunks, i = 0;
    chunks = Math.ceil(this.length / groupsize);

    while(i < chunks){
        sets[i] = this.splice(0, groupsize);
	i++;
    }
    return sets;
};

Using currying, to allow partial application:

const chunkArray = chunkSize => array => {
    return array.reduce((acc, each, index, src) => {
        if (!(index % chunkSize)) { 
            return [...acc, src.slice(index, index + chunkSize)];
        } 
        return acc;
        },
    []);
}

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];

const chunkArray3 = chunkArray(3);
const chunkArray5 = chunkArray(5);
chunkArray3(array);
// => [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12], [13, 14, 15]];
chunkArray5(array);
// => [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13, 14, 15]];

Here is mine, with generators approch. usefull when you want deal with bunch of data but keep small memory usage. And you can imagine handle an unlimited data flow with it ^^.

function* ennumerate(iterable, offset=0) {
  let i = offset;

  for (const item of iterable) {
    yield [i++, item];
  }
}

function* chunkor(iterable, size) {
  let chunk = [];

  for (const [index, item] of ennumerate(iterable, 1)) {
    chunk.push(item);

    if (index % size === 0) {
      yield chunk;
      chunk = [];
    }
  }

  if (chunk.length > 0) yield chunk;
}

/*
> [...chunkor([0,1,2,3,4,6,7,8,9], 2)]
[ [ 0, 1 ], [ 2, 3 ], [ 4, 6 ], [ 7, 8 ], [ 9 ] ]
> [...chunkor([0,1,2,3,4,6,7,8,9], 3)]
[ [ 0, 1, 2 ], [ 3, 4, 6 ], [ 7, 8, 9 ] ]
*/