chunkyMonkey.js

function chunkArrayInGroups(arr, size) {
  // Break it up.
  let chunks  = arr.length/size;

  let newArray = [];

  for (let i = 0; i < chunks ; i++){

    let chunkArray= arr.splice(0,size);

    newArray.push(chunkArray);

  }

  return newArray;

}

chunkArrayInGroups(["a", "b", "c", "d"], 2);