js switch...case语句与if...else性能比较

来源：互联网发布：centos yum 网卡驱动编辑：程序博客网时间：2024/05/21 12:49

■switch...case语句与if...else性能比较
var count=99999;

       function nIfElseTest(num)
       {
           var dBegin=new Date;
           //进行

           var iNum=0;
           for(var i=0;i<count;i++)
           {
               if(num==0)
               {
                   iNum=0;
               }
               else if(num==1)
               {
                   iNum=0;
               }
               else if(num==2)
               {
                   iNum=0;
               }
               else if(num==3)
               {
                   iNum=0;
               }
               else if(num==4)
               {
                   iNum=0;
               }
               else if(num==5)
               {
                   iNum=0;
               }
               else if(num==6)
               {
                   iNum=0;
               }
               else if(num==7)
               {
                   iNum=0;
               }
               else if(num==8)
               {
                   iNum=0;
               }
               else if(num==9)
               {
                   iNum=0;
               }
               else if(num==10)
               {
                   iNum=0;
               }
               else if(num==11)
               {
                   iNum=0;
               }
               else if(num==12)
               {
                   iNum=0;
               }
               else if(num==13)
               {
                   iNum=0;
               }
               else if(num==14)
               {
                   iNum=0;
               }
               else if(num==15)
               {
                   iNum=0;
               }
               else if(num==16)
               {
                   iNum=0;
               }
               else if(num==17)
               {
                   iNum=0;
               }
               else if(num==18)
               {
                   iNum=0;
               }
           }
           var dEnd=new Date;
           document.write("if...else耗时"+(dEnd.getTime()-dBegin.getTime())+"毫秒"+",num="+num+"<a href='javascript:history.back()'>继续测试</a>");
       }

       function nSwitchCaseTest(num)
       {
           var dBegin=new Date;
           //进行
           for(var i=0;i<count;i++)
           {
               switch(num)
               {
                   case 0:
                       iNum=0;break;
                   case 1:
                       iNum=0;break;
                   case 2:
                       iNum=0;break;
                   case 3:
                       iNum=0;break;
                   case 4:
                       iNum=0;break;
                   case 5:
                       iNum=0;break;
                   case 6:
                       iNum=0;break;
                   case 7:
                       iNum=0;break;
                   case 8:
                       iNum=0;break;
                   case 9:
                       iNum=0;break;
                   case 10:
                       iNum=0;break;
                   case 11:
                       iNum=0;break;
                   case 12:
                       iNum=0;break;
                   case 13:
                       iNum=0;break;
                   case 14:
                       iNum=0;break;
                   case 15:
                       iNum=0;break;
                   case 16:
                       iNum=0;break;
                   case 17:
                       iNum=0;break;
                   case 18:
                       iNum=0;break;
                   default:
               }
           }
           var dEnd=new Date;
           document.write("switch_case耗时"+(dEnd.getTime()-dBegin.getTime())+"毫秒"+",num="+num+"<a href='javascript:history.back()'>继续测试</a>");
       }
       </script>
   </head>
   <body>
       <button onClick="javaScript:nIfElseTest(0)">if0</button>
       <button onClick="javaScript:nIfElseTest(2)">if2</button>
       <button onClick="javaScript:nIfElseTest(4)">if4</button>
       <button onClick="javaScript:nIfElseTest(6)">if6</button>
       <button onClick="javaScript:nIfElseTest(8)">if8</button>
       <button onClick="javaScript:nIfElseTest(10)">if10</button>
       <button onClick="javaScript:nIfElseTest(12)">if12</button>
       <button onClick="javaScript:nIfElseTest(14)">if14</button>
       <button onClick="javaScript:nIfElseTest(16)">if16</button>
       <button onClick="javaScript:nIfElseTest(18)">if18</button>

       <p><a href="http://www.dreamdu.com/javascript/switch_case/">switch...case</a>测试</p>

       <button onClick="javaScript:nSwitchCaseTest(0)">switch0</button>
       <button onClick="javaScript:nSwitchCaseTest(2)">switch2</button>
       <button onClick="javaScript:nSwitchCaseTest(4)">switch4</button>
       <button onClick="javaScript:nSwitchCaseTest(6)">switch6</button>
       <button onClick="javaScript:nSwitchCaseTest(8)">switch8</button>
       <button onClick="javaScript:nSwitchCaseTest(10)">switch10</button>
       <button onClick="javaScript:nSwitchCaseTest(12)">switch12</button>
       <button onClick="javaScript:nSwitchCaseTest(14)">switch14</button>
       <button onClick="javaScript:nSwitchCaseTest(16)">switch16</button>
       <button onClick="javaScript:nSwitchCaseTest(18)">switch18</button>

0 0