Splitting array into two dimensional array based on size parameter

chunkyMonkey.js

// Write a function that splits an array (first argument) into groups the length of size (second argument) and returns them as a two-dimensional array.


function chunkArrayInGroups(arr, size) {
    var newArr = [];
        beginSlice = 0,
        endSlice = size;
    for (var i = 0; i < (arr.length/size); i++) {
        newArr.push(arr.join("").slice(beginSlice, endSlice).split());
        beginSlice += size;
        endSlice += size;
    }
    return newArr;
}
chunkArrayInGroups(["a", "b", "c", "d", "e", "f", "g"], 2)