html - 请问 在 css 中 expression 叫什么?我想系统学习一下.

Question

<span style="font-size: 16px;" data-find="_1">#mian img{
 max-width:170px;
 width:170px;
 width:expression(document.body.clientWidth>170?"170px":"auto");
 max-height:180px;
 height:180px;
 height:expression(document.body.clientWidth>180?"180px":"auto");
 overflow:hidden;
}
</span>

这里面普通的css我能看懂,
请问这个 expression 语法 是出自什么?
document.body.clientWidth 应该是js ,那么 expression 后面能跟jQuery 吗?

我想系统的学习一下..

就比如我问大家width:10px是什么代码? 
大家回答 css 就行了..

问 SELECT * FROM 是什么语法?
大家回答 SQL 语句就行了..

Answer 1

This can only be recognized by IE and is of little use

Answer 2

As the name suggests, css expression. It’s better not to learn this thing, it’s said in Yahoo’s military regulations Avoid CSS Expressions

Answer 3

It’s only available in IE, don’t learn it, you will be eliminated soon. If you have this energy, you might as well think more about how to build a good relationship with your leaders.