1 //生成从minNum到maxNum的随机数
 2 function randomNum(minNum,maxNum){ 
 3     switch(arguments.length){ 
 4     case 1: 
 5             return parseInt(Math.random()*minNum+1,10); 
 6     break; 
 7     case 2: 
 8         return parseInt(Math.random()*(maxNum-minNum+1)+minNum,10); 
10     break; 
11         default: 
12             return 0; 
13         break; 
14    } 
15 }