Question

Here is some code:
http://jsfiddle.net/T65E3/3/
I want to get an attr when i know class

$("#find").click(function() {
    $("#test").append($("#file").find("a.higlight").attr("rel"));
});

and html

 <div id="file">
<ul>
<li>
        <a class="higlight" rel="a">value_my</a>
        <a class="sth" rel="b">val</a>
        <a class="sth" rel="c">val2</a>
        <a class="sth" rel="d">val3</a>

</li>
</ul>
</div>

<button type="submit" id="find">find</button>
<div id="test"></div>

Answer 1

Your code as-is (if you include jQuery, your example had MooTools), works fine. There’s just one thing I’d like to point out.

$("#file").find("a.higlight").attr("rel") // 'a'

This will only return you the rel attribute of the first matched element. To get all the rel attributes (if there were multiple elements), you can use .map.

$("#file").find("a.sth").attr("rel") // 'b'

$("#file").find("a.sth").map(function(){
    return this.rel;
}).get(); // ['b','c','d']