2.5.Javascript--布尔型

 

<!DOCTYPE HTML>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <script type="text/javascript">
        var boolA = true;
        var boolB = false;
        
        var boolC = new Boolean(true);
        var boolD = new Boolean(false);
        
        document.write( boolA == boolC );
        document.write("</br>");
        document.write( boolB == boolD );
        document.write("</br>");

        
        if( boolA.constructor == Boolean ){
            document.write("布尔型");
        }
        
        //注释：如果省略 value 参数，或者设置为 0、-0、null、""、false、undefined 或 NaN，则该对象设置为 false。否则设置为 true（即使 value 参数是字符串 "false"）。
        
        var bool1 = new Boolean(0);
        var bool2 = new Boolean(-0);
        var bool3 = new Boolean(null);
        var bool4 = new Boolean("");
        var bool5 = new Boolean(false);
        var bool6 = new Boolean(undefined);
        var bool7 = new Boolean(NaN);
        
        document.write( bool1 + "<br/>");
        document.write( bool2 + "<br/>");
        document.write( bool3 + "<br/>");
        document.write( bool4 + "<br/>");
        document.write( bool5 + "<br/>");
        document.write( bool6 + "<br/>");
        document.write( bool7 + "<br/>");
        
    </script>
</body>
</html>



posted @ 2012-03-14 16:20  校长阿四  阅读(195)  评论(0)  编辑  收藏  举报