var bubbleSort = function(arr) {  for (var i = 0, len = arr.length; i < len - 1; i++) {    for (var j = i + 1; j < len; j++) {      if (arr[i] > arr[j]) {        var temp = arr[i];        arr[i] = arr[j];        arr[j] = temp;      }    }  }  return arr;};

var selectSort = function(arr) {  var min;  for (var i = 0; i < arr.length - 1; i++) {    min = i;    for (var j = i + 1; j < arr.length; j++) {      if (arr[min] > arr[j]) {        min = j;      }    }    if (i != min) {      swap(arr, i, min);    }    console.log(i + 1, ": " + arr);  }  return arr;};function swap(arr, index1, index2) {  var temp = arr[index1];  arr[index1] = arr[index2];  arr[index2] = temp;};

var insertSort = function(arr) {  var len = arr.length,    key;  for (var i = 1; i < len; i++) {    var j = i;    key = arr[j];    while (--j > -1) {      if (arr[j] > key) {        arr[j + 1] = arr[j];      } else {        break;      }    }    arr[j + 1] = key;  }  return arr;};

function shellSort(arr) {  if (arr.length < 2) {    return arr;  };  var n = arr.length;  for (gap = Math.floor(n / 2); gap > 0; gap = Math.floor(gap /= 2)) {    for (i = gap; i < n; ++i) {      for (j = i - gap; j >= 0 && arr[j + gap] < arr[j]; j -= gap) {        temp = arr[j];        arr[j] = arr[j + gap];        arr[j + gap] = temp;      }    }  }  return arr;};

function merge(left, right) {  var result = [];  while (left.length > 0 && right.length > 0) {    if (left[0] < right[0]) {      // shift()方法用于把數組的第一個元素從其中刪除，并返回第一個元素的值      result.push(left.shift());    } else {      result.push(right.shift());    }  }  return result.concat(left).concat(right);}function mergeSort(arr) {  if (arr.length == 1) {    return arr;  }  var middle = Math.floor(arr.length / 2),    left = arr.slice(0, middle),    right = arr.slice(middle);  return merge(mergeSort(left), mergeSort(right));}

var quickSort = function(arr) {　　  if (arr.length <= 1) {    return arr;  }  var pivotIndex = Math.floor(arr.length / 2);　  var pivot = arr.splice(pivotIndex, 1)[0];  var left = [];  var right = [];　　  for (var i = 0; i < arr.length; i++) {　　　    if (arr[i] < pivot) {　　　　　　      left.push(arr[i]);　　　　    } else {　　　　　　      right.push(arr[i]);　　　　    }　  }　　  return quickSort(left).concat([pivot], quickSort(right));};