jquery-ui - 在jquery中进行展开/折叠时如何识别索引

Question

这是我在进行展开/折叠时的以下代码，但我只想在其中进行展开/折叠操作时识别索引。

你能给我这个示例代码吗？

     $("#accordionDemo2").accordion({
            collapsible: true
        });

    <p><h2>Hi, This is Multiple Panel Demo1</h2></p>
    <div id="accordionDemo2">
        <h3><a href="#" class="acc">Section 1</a></h3>
        <div>
            <p>Hi, This is Section 1</p>
        </div>
        <h3><a href="#" class="acc">Section 2</a></h3>
        <div>
            <p>Hi, This is Section 2</p>
        </div>
        <h3><a href="#" class="acc">Section 3</a></h3>
        <div>
            <p>Hi, This is Section 3</p>        
        </div>
        <h3><a href="#" class="acc">Section 4</a></h3>
        <div>
            <p>Hi, This is Section 4</p>
        </div>
    </div>

Answer 1

http://docs.jquery.com/UI/Accordion#option-active

活动元素的选择器。设置为 false 以在开始时不显示。需要可折叠：是的。

//getter
var active = $( ".selector" ).accordion( "option", "active" );
//setter
$( ".selector" ).accordion( "option", "active", 2 );