randomColor_foshan_2(){...}函数存在缺陷

以下是页面打开测试文件的结果

 

randomColor_foshan_2(){...}函数存在缺陷

1. randomColor_foshan_2(){...}函数

	



	/****







	 * name:我佛山人







	 * qq:52739105







	 * blog:







	 */







	function randomColor_foshan_2(){







		return (new Date().getTime() & 0xffffff).toString(16);







	}



	

2. 测试缺陷

var date = new Date();

date: Sun Jun 06 2010 15:41:09 GMT+0800 (China Standard Time)

date.getTime(): 1275810069957

date = date.getTime().toString(2);

date: 10010100100001100001101001011110111000101

date = date.substring(0, date.length-24)+"000000000000000000000000";//24个0

date: 10010100100001100000000000000000000000000

date = parseInt(date,2);

date: 1275806613504

date = new Date(date);

date: Sun Jun 06 2010 14:43:33 GMT+0800 (China Standard Time)

date.getTime(): 1275806613504

(date.getTime()&0xffffff): 0

(date.getTime()&0xffffff).toString(16): 0

3. 测试结论

从以上的测试中可以看到：

(1) randomColor_foshan_2(){...}函数存在返回值为"0"(不是6个代表颜色的字符)的可能性。

(2) randomColor_foshan_2(){...}函数返回"0"的可能性很小，每隔 0xffffff + 1 = 16777216 ms （大约 4.66小时） 发生一次， 。

 

 

以下是测试文件的源代码

 

<?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>randomColor_foshan_2_bugTest</title>
<style type="text/css">
    pre{
        border: 1px dashed #ccc;
    }
    p strong {
        background: #303030;
        color: #fff;
        font-weight: normal;
        display: block;
        padding: 10px 0;
    }
   
    p u {
        background: #f99;
        color: #000;
        font-weight: normal;
        display: block;
        padding: 3px 0;
        text-decoration: none;
    }
</style>
</head>
<body>
<h1>randomColor_foshan_2(){...}函数存在缺陷</h1>
<h3>1. randomColor_foshan_2(){...}函数</h3>
<div>
    <pre>
       
    /****
     * name:我佛山人
     * qq:52739105
     * blog:
     */
    function randomColor_foshan_2(){
        return (new Date().getTime() & 0xffffff).toString(16);
    }
       
    </pre>
   
</div>
<h3>2. 测试缺陷</h3>
<div id="debug"></div>
<h3>3. 测试结论</h3>
<div>
<p>从以上的测试中可以看到：</p>
<p>(1) randomColor_foshan_2(){...}函数存在返回值为"0"(不是6个代表颜色的字符)的可能性。</p>
<p>(2) randomColor_foshan_2(){...}函数返回"0"的可能性很小，每隔  0xffffff + 1 = 16777216 ms （大约 4.66小时） 发生一次， 。</p>
</div>
<script type="text/javascript">
    //
    function debug(s){
        document.getElementById("debug").innerHTML += "<p>" + s + "</p>";
    }
   
    /****
     * name:我佛山人
     * qq:52739105
     * blog:
     */
    function randomColor_foshan_2(){
        return (new Date().getTime() & 0xffffff).toString(16);
    }
   
    window.onload = function(){
        var date = new Date();
        debug("<strong>var date = new Date();</strong>");
        debug("date: " + date);
        debug("date.getTime(): " + date.getTime());
        //
        date = date.getTime().toString(2);
        debug("<strong>date = date.getTime().toString(2);</strong>");
        debug("date: " + date);
        //
        date = date.substring(0, date.length - 24) + "000000000000000000000000";//24个0
        debug('<strong>date = date.substring(0, date.length-24)+"000000000000000000000000";//24个0</strong>');
        debug("date: " + date);
        //
        date = parseInt(date, 2);
        debug("<strong>date = parseInt(date,2);</strong>");
        debug("date: " + date);
        //
        date = new Date(date);
        debug("<strong>date = new Date(date);");
        debug("date: " + date);
        //
        debug("date.getTime(): " + date.getTime());
        debug("(date.getTime()&0xffffff): " + (date.getTime() & 0xffffff));
        debug("<u>(date.getTime()&0xffffff).toString(16): " + (date.getTime() & 0xffffff).toString(16) + "</u>");
        //
    }
</script>
</body>
</html>

 

 

 

 

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