Returning a Chunk Array in JS

A chunked array is an array of a size, given an array arr.

A chunked array contains the original elements from arr with subarrays of length size. The last chunk can be less than the size if the arr is not evenly divisble.

To solve this, we create a finalarr variable to store the new array.

We create a for loop, starting i=0 but increment it by i+=size. The block uses slice() to create a shallow copy of the original arr and then pushes each subarray of length size into finalarr.

Then, we can still push the final subarray that is not the exact size because slice()’s second parameter end has the following condition on MDN:

If end >= array.length or end is omitted, array.length is used, causing all elements until the end to be extracted.

Example 1 demonstrates the arr has been split into subarrays with 3 elements. However, only two elements are left for the 2nd subarray.

var chunk = function(arr, size) {
    let finalarr = []
    
    for (let i=0; i < arr.length; i+=size) {
        let slicedarr = arr.slice(i, i+size);
        finalarr.push(slicedarr);
    }

    return finalarr;

};

Example 1:

Input: arr = [1,9,6,3,2], size = 3
Output: [[1,9,6],[3,2]]