Why doesn't index() working as expected

Question

HTML:

Div 1
Div 2
 
Div 3
 
<         


        

Answer 1

why the output is 4, 6, 8, 10

$(this).index() returns the index of the element relative to its siblings, not to the selected elements. The br and .divX elements are siblings as well!

It looks like you want:

var $tests = $(".test");

$tests.each(function(){
    var i = $tests.index(this);
    alert(i);
});

or simpler:

$(".test").each(function(i){
    alert(i);
});