043Math对象.html

﻿<!DOCTYPE html>
<html>
     <head>
          <meta charset="UTF-8">
          <title></title>
     </head>
     <style type="text/css">
      
     </style>
	 <script src="js/common.js"></script>
     <body>
        <span id="checkcode"></span><button onclick="createCode(10)">生成验证码</button>
         
     </body>
     <script type="text/javascript">
		//for(var i=0; i<10; i++) log( randomInt(99,100) );
		//log(123);
		function createCode(len){
		
			var str = "";
			for(var i=0; i<len; i++) {
				
				/*
				for( var ascii = randomInt(48,90); ascii >=58 && ascii <=64 ; ascii = randomInt(48,90)) {
					
				}
				*/
				
				var ascii = randomInt(48,90);
				while(ascii >=58 && ascii <=64) { //随机结果不符合要求
					ascii = randomInt(48,90);
				}
				
				//console.log(ascii);
				str += String.fromCharCode(ascii);			
			}
			console.log(str);
		}
		
		
		var count = 0; //总攻击次数
		var pcount = 0; //暴击次数
		var fixp =  0.2; //期望概率
		var c = 0.0557; //种子
		
		for(var i=0; i<10000; i++) {
			var num = Math.random();
			if(num <= fixp){
				//暴击发生了
				pcount++;
				
				fixp = c;
				
			} else {
				fixp += c;
			}
			count++;
		}
		
		console.log(pcount/count);
		
		
     </script>
</html>