How to find latest Div ID counter

I've a bunch of divs with each div id starting with a common name and ending wiht a incremental number:

<div id="thisismydiv1"></div>
<div id="thisismydiv2"></div>
<div id="thisismydiv3"></div>
开发者_开发知识库<div id="thisismydiv4"></div> 

How do I find out the latest number i.e. 4 using jQuery?

var token = "thisismydiv";
var id = $('div[id^="' + token + '"]').last().id;
id = id.replace(token, '');
alert(id);

Demo: jsFiddle

$("div").last().attr('id');

or

$("div:last").attr('id');

.last() or :last will do it

I think the last selector may help you - http://api.jquery.com/last-selector/

$('div:last');

Use the [^=] selector to find the elements where the id starts with that string, get the numeric part of the id, parse it, and check for the highest value:

var highest = 0;
$('[id^="thisismydiv"]').each(function(){
    var id = parseInt(this.id.substr(11));
    if (id > highest) highest = id;
});

alert(highest);

Demo: http://jsfiddle.net/Guffa/cdQ9C/

If the parent container only has these divs and your ids start at one and increment by one, you could just get the children count of the parent.

$("parent").children().length;

If not, you can use the last selector like others have mentioned.

$('div[id^="thisismydiv"]').last().attr('id').match(/\d+/);

Will return 4.

Demo: http://jsfiddle.net/rSSG8/