此HTML代码是什么意思？

Question

I've viewed in some source code and found something like this:

<div class="classname {height: 300px; width: 200px}"></div>

I know that element styling is available by using the style="" attribute.

Can you please tell me what this code means?

Answer 1

It means nothing per se in the HTML specification. The website you were looking at was probably using some javascript code which interprets this class attribute and performs some actions based on the values it has parsed. Without javascript this does nothing. In HTML the class attribute is used to specify a CSS classname to be associated to this element.

For example the jQuery.validate plugin uses similar technique allowing you to specify inline validation rules. Actually the plugin uses data-* attributes instead of class which is semantically more correct for those kind of tasks.