javascript array split chunk

function splitArrayIntoChunksOfLen(arr, len) {
  var chunks = [], i = 0, n = arr.length;
  while (i < n) {
    chunks.push(arr.slice(i, i += len));
  }
  return chunks;
}
var alphabet=['a','b','c','d','e','f'];
var alphabetPairs=splitArrayIntoChunksOfLen(alphabet,2); //split into chunks of two

const chunk = (arr, size) => arr.reduce((acc, e, i) => (i % size ? acc[acc.length - 1].push(e) : acc.push([e]), acc), []);

// Examples
chunk([1, 2, 3, 4, 5, 6, 7, 8], 3);     // [[1, 2, 3], [4, 5, 6], [7, 8]]
chunk([1, 2, 3, 4, 5, 6, 7, 8], 4);     // [[1, 2, 3, 4], [5, 6, 7, 8]]

let input = [1,2,3,4,5,6,7,8,9];
let chunked = []
let size = 2;

for (let i = 0;  i < input.length; i += size) {
  chunked.push(input.slice(i, i + size))
}
console.log(chunked)

//#Source https://bit.ly/2neWfJ2 
const chunk = (arr, size) =>
  Array.from({ length: Math.ceil(arr.length / size) }, (v, i) =>
    arr.slice(i * size, i * size + size)
  );
console.log(chunk([1, 2, 3, 4, 5], 2));

let input = [1,2,3,4,5,6,7,8];
let chunked = []
let size = 2;

Array.from({length: Math.ceil(input.length / size)}, (val, i) => {
  chunked.push(input.slice(i * size, i * size + size))
})

console.log(chunked);