how to addClass to its equal index .....(JQUERY)

<ul>
   <li>Index 0</li>
   <li>Index 1</li>
   <li>Index 2</li>
</ul>
<div>
     <a>Index 0</a>
     &l开发者_开发百科t;a>Index 1 (If i click this this this i want to addClass to it to LI with the same index of this )</a>
     <a>Index 2</a>
</div>

---

You can invoke jQuerys .index()^help method for that purpose. It returns the index relative the the siblings of the current node. To find the li node with the according index, use .eq()^help

$('a').click(function() {
   $('ul li').eq($(this).index()).addClass('your_new_class');
});

Demo: http://www.jsfiddle.net/2rFn3/

Referring to your comment

$('a').click(function() {
   $('ul li').eq($(this).index()).addClass('your_new_class').siblings().removeClass('your_new_class');
});

Demo: http://www.jsfiddle.net/2rFn3/1/

---

$("a").click(function() {
   //Remove classes from other li (per comment)
    $("ul li").removeClass("class");

   //Now update the clicked item
   var length = $(this).prevAll().length;
   $("ul li:eq(" + length + ")").addClass("class");
});

---

firstly you can add an id on the div and the li to make it easier to select.

div#start and ul#target

$("div#start > a").bind("click dblclick",function(){
    $("ul#target:nth-child("+$(this).index()+")").addClass("whatever");    
});