js实现常用排序算法

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

 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);  } }};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; }}; 

 var shellSort = function (arr) { var gaps = [5, 3, 1]; for (var g = 0; g < gaps.length; ++g) {  for (var i = gaps[g]; i < arr.length; ++i) {   var temp = arr[i];   for (var j = i; j >= gaps[g] && arr[j - gaps[g]] > temp; j -= gaps[g]) {    arr[j] = arr[j - gaps[g]];   }   arr[j] = temp;  } }}; 

 function mergeSort(arr) { if (arr.length < 2) {  return; } var step = 1; var left, right; while (step < arr.length) {  left = 0;  right = step;  while (right + step <= arr.length) {   mergeArrays(arr, left, left + step, right, right + step);   left = right + step;   right = left + step;  }  if (right < arr.length) {   mergeArrays(arr, left, left + step, right, arr.length);  }  step *= 2; }}function mergeArrays(arr, startLeft, stopLeft, startRight, stopRight) { var rightArr = new Array(stopRight - startRight + 1); var leftArr = new Array(stopLeft - startLeft + 1); k = startRight; for (var i = 0; i < (rightArr.length - 1); ++i) {  rightArr[i] = arr[k];  ++k; } k = startLeft; for (var i = 0; i < (leftArr.length - 1); ++i) {  leftArr[i] = arr[k];  ++k; } rightArr[rightArr.length - 1] = Infinity; // 哨兵值 leftArr[leftArr.length - 1] = Infinity; // 哨兵值 var m = 0; var n = 0; for (var k = startLeft; k < stopRight; ++k) {  if (leftArr[m] <= rightArr[n]) {   arr[k] = leftArr[m];   m++;  }  else {   arr[k] = rightArr[n];   n++;  } }} 

 var quickSort = function(arr, left, right) { var i, j, t, pivot; if (left >= right) {  return; } pivot = arr[left]; i = left; j = right; while (i != j) {  while (arr[j] >= pivot && i < j) {   j--;  }  while (arr[i] <= pivot && i < j) {   i++;  }  if (i < j) {   t = arr[i];   arr[i] = arr[j];   arr[j] = t;  } } arr[left] = arr[j]; arr[j] = pivot; quickSort(arr, left, i - 1); quickSort(arr, i + 1, right);}