Avoid linking to anchors that do not exist

A common web design pattern is to use a named anchor to show an element via JavaScript, e.g.

<a href="#foo" onclick="$('.bar').toggle();">Click me</a>
<div class="bar">
    This is some content.
</div>

In these cases, the anchor (#foo) should point to the id of the hidden element:

<a href="#foo" onclick="$('#foo').toggle();">Click me</a>
<div id="foo">
    This is some content.
</div>

This way the semantic intent of the link is preserved, even without JavaScript. Note that doing so may require modification to your script, to prevent automatic scrolling to the named anchor.