Chunk array by given size.

array_chunk.js

function chunk(arr, chunkSize) {
    let result = [];

    function getChunkedArr(arrToChunk) {
        let res = [];
        for(let i = 0; i < arrToChunk.length; i++) {
            res.push(arrToChunk[i]);
        }
        return res;
    }

    for(let i = 0; i < arr.length;) {
        const chunkedArr = arr.slice(i, i + chunkSize);
        result.push(getChunkedArr(chunkedArr));
        i += chunkSize;
    } 
    return result;
};

console.log(chunk([1,2,3,4,5,6], 2)) // [[1,2], [3,4], [5,6]];
console.log(chunk([1,2,3,4,5], 2)) // [[1,2], [3,4], [5]];