具体解释看代码，代码如下

   1:  //主函数

   2:  function main() {

   3:      var quickTimeArray = new Array();

   4:      var mergeTimeArray = new Array();

   5:      for (var i = 1; i <= 20; i++) {

   6:   

   7:          

   8:          var array = getRandomArrayEasy(5000*i    );

   9:          var array2 = array.slice(0);

  10:          

  11:   

  12:          var startTime = new Date().getTime();

  13:          doMergeSort(array);

  14:          

  15:          

  16:          var endTime = new Date().getTime();

  17:          mergeTimeArray.push(endTime - startTime);

  18:   

  19:   

  20:   

  21:          var startTime = new Date().getTime();

  22:          

  23:          doQuickSort(array2);

  24:          

  25:   

  26:          var endTime = new Date().getTime();

  27:          

  28:          quickTimeArray.push(endTime - startTime);

  29:          

  30:      }

  31:      draw(quickTimeArray,mergeTimeArray);

  32:   

  33:   

  34:  }

  35:   

  36:   

  37:   

  38:  //归并排序

  39:  function doMergeSort(array) {

  40:      mergeSort(array, 0, array.length - 1);

  41:  }

  42:   

  43:  function mergeSort(array, low, high) {

  44:      var mid = 0;

  45:      if (low < high) {

  46:          mid = parseInt((low + high) / 2);

  47:          mergeSort(array, low, mid);

  48:          mergeSort(array, mid + 1, high);

  49:          merge(array, low, mid, high);

  50:      }

  51:  }

  52:   

  53:  function merge(array, low, mid, high) {

  54:      var tempArray = new Array();

  55:      var i = low;

  56:      var j = mid + 1;

  57:      while (true) {

  58:          var small = 0;

  59:          if (array[i] < array[j]) {

  60:              small = array[i]

  61:              i++;

  62:          } else {

  63:              small = array[j];

  64:              j++;

  65:          }

  66:          tempArray.push(small);

  67:          if (i > mid) {

  68:              //i结束，只需要复制i到j-1就行了

  69:              for (var k = low; k < j; k++) {

  70:                  array[k] = tempArray.shift();

  71:              }

  72:              break;

  73:          }

  74:          if (j > high) {

  75:              for (var k = i; k <= mid; k++) {

  76:                  tempArray.push(array[k]);

  77:              }

  78:              for (var k = low; k <= high; k++) {

  79:                  array[k] = tempArray.shift();

  80:              }

  81:              break;

  82:          }

  83:   

  84:      }

  85:   

  86:  }

  87:   

  88:  //快速排序

  89:  //return 排序好的数组

  90:  function doQuickSort(array) {

  91:      quickSort(array, 0, array.length - 1);

  92:  }

  93:   

  94:  function quickSort(array, low, high) {

  95:      var w = 0;

  96:      if (low < high) {

  97:          w = split(array, low, high);

  98:          quickSort(array, low, w - 1);

  99:          quickSort(array, w + 1, high);

 100:      }

 101:  }

 102:   

 103:  //快速排序的划分算法

 104:  //return 划分好的数组

 105:  function split(array, low, high) {

 106:      var temp = array[low];

 107:      var temp2 = getSplitingElementIndex(array, low, high);

 108:      array[low] = array[temp2];

 109:      //获得划分元素的位置

 110:      array[temp2] = temp;

 111:      var i = low;

 112:      var x = array[low];

 113:      for (var j = low + 1; j <= high; j++) {

 114:          if (array[j] <= x) {

 115:              i++;

 116:              if (i != j) {

 117:                  var temp3 = array[i];

 118:                  array[i] = array[j];

 119:                  array[j] = temp3;

 120:              }

 121:          }

 122:      }

 123:      var temp4 = array[low];

 124:      array[low] = array[i];

 125:      array[i] = temp4;

 126:      return i;

 127:   

 128:  }

 129:   

 130:  //寻找划分元素

 131:  //return 划分元素在数组中的位置

 132:  //param array 数组

 133:  //param low 下限

 134:  //param high 上限

 135:  function getSplitingElementIndex(array, low, high) {

 136:      var mid = low + parseInt((low + high) / 2);

 137:      if (array[mid] > array[low])//array[mid] 为第二大时返回mid

 138:      {

 139:          if (array[mid] < array[high]) {

 140:              return mid;

 141:          } else {

 142:              if (array[high] < array[low]) {

 143:                  return low;

 144:              } else {

 145:                  return high;

 146:              }

 147:          }

 148:      } else {

 149:          if (array[low] < array[high])//array[low] 为第二大是返回low

 150:          {

 151:              return low;

 152:          } else {

 153:              if (array[high] > array[low]) {

 154:                  return high;

 155:              } else {

 156:                  return low;

 157:              }

 158:          }

 159:      }

 160:  }

 161:   

 162:  //size数组大小

 163:  //floor数据下限 floor>=0;

 164:  //upper数据上限

 165:  //return 数组对象

 166:  function getRandomArray(size, floor, upper) {

 167:      if (floor < 0 || upper < 0)

 168:          return null;

 169:      var temp = upper - floor;

 170:      var array = new Array();

 171:      for (var i = 0; i < size; i++) {

 172:          array[i] = parseInt(Math.random() * temp + floor);

 173:      }

 174:      return array;

 175:   

 176:  }

 177:   

 178:  //封装好的默认范围为0到100000的getRandomArray

 179:  function getRandomArrayEasy(size) {

 180:      return getRandomArray(size, 0, 100000);

 181:  }

 182:   

 183:  //画图

 184:  function draw(QTArray,MTArray) {

 185:      var quickTr = document.getElementById("quickSort");

 186:      var mergeTr = document.getElementById("mergeSort");

 187:      for(var i=0;i<QTArray.length;i++)

 188:      {

 189:          var th  = document.createElement('th');

 190:          th.innerHTML=QTArray[i];

 191:          quickTr.appendChild(th);

 192:          

 193:          var th2  = document.createElement('th');

 194:          th2.innerHTML=MTArray[i];

 195:          mergeTr.appendChild(th2);

 196:      }

 197:   

 198:  }

 199:   

 200:   

附上调用的页面

   1:  <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"

   2:  "http://www.w3.org/TR/html4/strict.dtd">

   3:   

   4:  <html xmlns="http://www.w3.org/1999/xhtml" lang="en">

   5:      <head>

   6:          <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

   7:          <title>index</title>

   8:          <meta name="author" content="Jabba" />

   9:          <!-- Date: 2012-11-15 -->

  10:      </head>

  11:      <body >

  12:          <script type="text/javascript" src="sort.js"></script>

  13:          <div align= "center">

  14:              <input type="button" value="start" onclick="main()"/>

  15:          </div>

  16:          <div align="center">

  17:              <table id="table" rows="3" cols="21" border="1">

  18:                  <tr>

  19:                      <th>排序算法</th>

  20:                      <th colspan="20">排序时间(毫秒)</th>

  21:                  </tr>

  22:                  <tr id="mergeSort">

  23:                      <td>归并排序</td>

  24:                  </tr>

  25:                  <tr id="quickSort">

  26:                      <td>快速排序</td>

  27:                  </tr>

  28:              </table>

  29:          </div>

  30:   

  31:      </body>

  32:   

  33:  </html>

  34: