jsでarray_chunk

http://php.net/manual/ja/function.array-chunk.php
こういうのほしかったので。

function arrayChunk(input, size) {
  var ret = []
    , x = -1;
  input.forEach(function(val, i) {
    var y = i % size;
    y === 0 ? ret[++x] = [val] : ret[x][y] = val;
  });
  return ret;
}

var a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
console.log( arrayChunk(a, 2) ); // => [ [ 1, 2 ], [ 3, 4 ], [ 5, 6 ], [ 7, 8 ], [ 9, 10 ] ]
console.log( arrayChunk(a, 3) ); // => [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ], [ 10 ] ]