<a href="javascript:void(0)" onclick="doSomething();returnfalse;">Link</a>

这是一个曾经被多次讨论过的问题，长期以来，我也一直是这样写的。读了 a href=”javascript:void(0);” — avoid the void 之后，我认同了作者的意见。下面的写法确实更合理：

<a href="#" onclick="doSomething();returnfalse;">Link</a>

或者

<script type="javascript">
function doSomething() {
  //doSomething
  returnfalse;
}
</script>
<a href="#" onclick="return doSomething();">Link</a>

以往大家不使用"#"的问题是，这将导致点击链接时页面跳回页面顶部，但通过 return false 语句将使得浏览器忽略链接的默认动作，从而避免了此问题。

youngpup 更有意思，他在How to Create Pop-Up Windows 中言辞激烈的倡导大家永远永远永远不要使用 javascript: 伪协议：

Never, ever, ever use the javascript: pseudo-protocol for anything, ever ever ever ever again. Please. Pretty please.

他的解决方案是：

<a 
  href="http://google.com/" 
  onclick="window.open(this.href, 'popupwindow', 
  'width=400,height=300,scrollbars,resizable'); 
  returnfalse;">

这样的好处就是可以保存到书签或者收藏夹，可以左键单击，也可以右键使用！

Remarks

The property initially returns the host name of the server from which the page is served. The property can be assigned the domain suffix to allow sharing of pages across frames. For example, a page in one frame from home.microsoft.com and a page from www.microsoft.com initially would not be able to communicate with each other. However, by setting the domain property of both pages to the suffix "microsoft.com", you ensure that both pages are considered secure and access is available between the pages.

When you set the domain property, use the domain name determined by the server rather than by the client browser.

All the pages on different hosts must have the domain property explicitly set to the same value to communicate successfully with each other. For example, the value of the domain property of a page on the host microsoft.com would be "microsoft.com" by default. It might seem logical that if you set the domain property of a page on another host named msdn.microsoft.com to "microsoft.com," that the two pages could communicate with each other. However, this is not the case unless you have also explicitly set the domain property of the page on microsoft.com to "microsoft.com".

Furthermore, this property cannot be used to allow cross-frame communication among frames with different domain suffixes. For example, a page in one frame from www.microsoft.com and a page in another frame from www.msn.com would not be able to communicate with each other even if the domain property of both pages was set to the suffix "microsoft.com".

Security Alert  Using this property incorrectly can compromise the security of your Web site. Set the domain property only if you must allow cross-domain scripting. Use a value determined on the server. Setting this property to a value determined on the client (like through the location object) could expose your site to attack from another site through Domain Name System (DNS) manipulation. For more information, see Security Considerations: Dynamic HTML.

For more information on domain security, see About Cross-Frame Scripting and Security.