How to create 2D array dynamically with the ES6 approach? - arrays

Question

I've been trying to create 2D arrays from an array dynamically with a function; however, I couldn't break out of the ES3 old school approach. Does anybody know how to refactor the following code using the ES6 approach?
const nums = [1,2,3,4,5,6,7,8,9,10,11,12];
const letters = ['a','b','c','d','e','f','g','h','i'];
function create2D(arr,set) {
const result = [];
for (let i = 0; i < arr.length; i+=set) {
const rows = arr.slice(i,i+set);
result.push(rows);
}
return result;
}
console.log(create2D(nums,4)); // [ [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ], [ 9, 10, 11, 12 ] ]
console.log(create2D(letters,3)); // [ [ 'a', 'b', 'c' ], [ 'd', 'e', 'f' ], [ 'g', 'h', 'i' ] ]
I've only gotten this far with "reduce" and couldn't find out how to replicate the addition assignment "i+=set" from the for loop. This is what I have so far...
function create2D(arr,set) {
return arr.reduce((result,item,i) => {
result.push(arr.slice(i,i+set));
return result;
},[]);
}
console.log(create2D(nums, 4)); // [ [1, 2, 3, 4],[2, 3, 4, 5],[3, 4, 5, 6], ...]

Answer 1

You were pretty close. Just need to modify it slightly:
const nums = [1,2,3,4,5,6,7,8,9,10,11,12];
const letters = ['a','b','c','d','e','f','g','h','i'];
function create2D(arr,set) {
return arr.reduce((result,item,i) => {
let startVal = i*set //We want to jump through the startPoints. Not iterate through them all
if (startVal < arr.length-1) {
result.push(arr.slice(startVal,startVal+set));
}
return result;
}, []);
}
console.log(create2D(nums, 4)); // [ [1, 2, 3, 4],[2, 3, 4, 5],[3, 4, 5, 6], ...]
console.log(create2D(nums, 3));
console.log(create2D(letters, 3));