Get array index number based on array element id

Question

I have an array with objects, each object, a div, has an id. Can I retrieve the array index number of a given object based on its id using this?

var index = ar.map(function(el) {
  return el. ??
}).indexOf('objectID4'); 

Answer 1

Like this:

var index = ar.map(function(el) {
  return el.id;
}).indexOf('objectID4');

working example: http://jsfiddle.net/bvT6B/

Answer 2

check for below code

var ar = [{'id':'objectId1','foo':'bar'},{'id':'objectId4','foo':'bar'}]

var index = ar.map(function(el) {
   return el.id;
}).indexOf('objectId4');

alert(index);

Or you can see in http://jsfiddle.net/VJrWc/

If this is not you want the share some more code and clear your goal.

Answer 3

It this what you want?

<div id="x1" class='foo'></div>
<div id="x2" class='foo'></div>
<div id="x3" class='foo'></div>

<div id="res"></div>
<script>
function getIndexOfById(uid) {
    var id = null;
    $('.foo').each(function() {
        if ($(this).attr('id') == uid) {id = $(this).index();}
    });
    return id;
}

$('#res').html(getIndexOfById('x1') + ' / ' + getIndexOfById('x2') + ' / ' + getIndexOfById('x3'));
</script>

The result is

0 / 1 / 2