SOURCE

function bubbleSort (arr) {
  let len = arr.length;
  for (let i = 0; i < len - 1; i++) {
    let swap = false;
    for  (let j = i + 1; j < len; j++) {
      if (arr[j] < arr[j - 1]) {
        var temp = arr[j];
        arr[j] = arr[j - 1];
        arr[j - 1] = temp;
        swap = true;
      }
    }
    console.log( i + '次：' + arr);
    if (!swap) {
      break;
    }
  }
  console.log(arr);
}
bubbleSort([2,5,3,8,4,5,9,34])