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javascript void

javascript:void(0) Meaning

We often use code like javascript:void(0), so in JavaScript javascript:void What does (0) mean?

The most critical thing in javascript:void(0) is the void keyword. void is a very important keyword in JavaScript. This operator specifies to calculate an expression but does not return a value.


##The syntax format is as follows:

< ;head>

<script type="text/javascript">
<!--
void func()
javascript:void func()

or

void(func())
javascript:void(func())
//-->
</script>
</head>

The following code creates a hyperlink that does nothing when the user clicks on it.

<!DOCTYPE html> 
<html>
<head> 
<meta charset="utf-8"> 
<title>php中文网(php.cn)</title> 
</head> 
<body>
    <a href="javascript:void(0)">单此处什么也不会发生</a>
</body>
</html>

When the user links, void(0) evaluates to 0, but has no effect on Javascript.

In the following example, a warning message is displayed after the user clicks the link:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<script type="text/javascript">
<!--
//-->
</script>
</head>
<body>
<p>点击以下链接查看结果:</p>
<a href="javascript:void(alert('Warning!!!'))">点我!</a>
</body>
</html>

Run the program and try it


In the following example, parameter a will return undefined:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>php中文网(php.cn)</title>
    <script type="text/javascript">
        function getValue(){
            var a,b,c;
            a = void ( b = 5, c = 7 );
            document.write('a = ' + a + ' b = ' + b +' c = ' + c );
        }
    </script>
</head>
<body>
<p>点击以下按钮查看结果:</p>
<form>
    <input type="button" value="点我" onclick="getValue();" />
</form>
</body>
</html>

Run the program and try it


The difference between href="#" and href="javascript:void(0)"

# Contains With a location information, the default anchor is #top, which is the top of the web page.

And javascript:void(0) only represents a dead link.

When the page is very long, # will be used to locate the specific location of the page. The format is: # + id.

If you want to define a dead link, please use javascript:void(0).

Example

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>php中文网(php.cn)</title>
</head>
<body>
<a href="javascript:void(0);">点我没有反应的!</a><br/>
<a href="#pos">点我定位到指定位置!</a>
<br>
...
<br>
<p id="pos">尾部定位点</p>
</body>
</html>

Run the program and try it


Next Section

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>php中文网(php.cn)</title> <script type="text/javascript"> <!-- //--> </script> </head> <body> <p>点击以下链接查看结果:</p> <a href='javascript:alert("Warning!!!");'>点我!</a> </body> </html>
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