void 运算表达式并忽略其返回值,比如void
(1+2),void (0)
1 <html>
2
3 <head>
4
5 <meta http-equiv="content-type" charset="utf-8"/>
6
7 <script type="text/javascript">
8
9 alert(typeof(void(0))); //void(0) 计算值为0,由于忽略返回值,typeof类型为:undefined
10
11 </script>
12
13 </head>
14
15 <body>
16
17 1.用onclick事件来灵活处理;2.void(expression)<br>
18
19 <a href="javascript:void(0);" onclick="location.href=‘http://www.baidu.com‘;">百度</a>
20
21 <a href="javascript:void(location.href=‘http://www.google.com‘)">谷歌</a>
22
23 </body>
24
25 </html>
2.typeof
返回变量或值的类型,比如 typeof(void 1+2)
,typeof(void(1+2))
由于运算符优先级,void 1+2 的运算过程为:
void(1+2)的计算过程为:
3.new用于创建指定类的对象实列
4.delete删除实列属性,对于delete有几点必须注意:
1.只删除实列属性,而不会删除对象
1 <html>
2 <head>
3 <meta http-equiv="content-type" charset="utf-8"/>
4 <script type="text/javascript">
5 var parent={};
6 var son={age:10};
7 parent.son=son;
8 alert(parent.son.age);//10
9 delete parent.son;
10 alert(parent.son);//undefined
11 alert(son.age);//10
12 </script>
13 </head>
14 <body>
15 </body>
16 </html>
Ps:未完带补充....
时间: 2024-08-06 03:43:36