More Alex & Pancho pair programming

mirrorChunk.js

// https://www.codewars.com/kata/5852d0d463adbd39670000a1/solutions/javascript

function goLeft(arr, n) {
  let chunk = [];

  if (n >= arr.length) {
    return [arr];
  }
  let endIndex = arr.length - 1;
  for (let i = n - 1; i >= 0; i--) {
    chunk.push(arr[endIndex - i]);
  }

  let remainder = arr.slice(0, -n);
  return goLeft(remainder, n * 2).concat([chunk]);
}

function goRight(arr, n) {
  let chunk = [];

  if (n >= arr.length) {
    return [arr];
  }
  for (var i = 0; i < n; i++) {
    chunk.push(arr[i]);
  }

  let remainder = arr.slice(i);
  return [chunk].concat(goRight(remainder, n * 2));
}

function mirroredExponentialChunks(arr){
  let chunked = [];

  if (arr.length % 2 === 0) {
    var n = 2;
    var middle = arr.length / 2;

    let before = [];
    before.push(arr[middle-2]);
    before.push(arr[middle-1]);

    let after = [];
    after.push(arr[middle]);
    after.push(arr[middle+1]);
    
    chunked.push(before, after);
    var right = arr.slice(middle + 2);
    var left  = arr.slice(0, middle - 2);
  } else {
    var middle = Math.floor(arr.length / 2)
    var n = 1;
    chunked.push([arr[middle]]);
    var right = arr.slice(middle + 1);
    var left  = arr.slice(0, middle);
  }
  
  chunked = goLeft(left, n * 2).concat(chunked).concat(goRight(right, n * 2));

  return chunked;
}
arr = [1,2,3,4,5,6,7,8,9,10, 11, 12, 13, 14, 15, 16, 17] 
mirroredExponentialChunks(arr)