insertion sort（插入排序）

function insertionSort (arr) {
  let len = arr.length;
  let j = 0, tmp = 0;

  for (let i = 1; i < len; i++) {
    j = i;
    tmp = arr[i];

    while (j > 0 && arr[j-1] > tmp) {
      arr[j] = arr[j-1];
      j--;
    }

    arr[j] = tmp;
  }
}