Question

Demo page for testing: http://jsfiddle.net/rCKzs/

<script type="text/javascript">
    $(document).ready(function() {  
        alert( $("#test").width() );          
    });
</script>

..

<div id="test">content</div>

If I remove the jQuery Mobile, then it is okay, otherwise it return 0.

Answer 1

Do not use document.ready with jQM:

• http://jquerymobile.com/demos/1.0/docs/api/events.html

Important: Use pageInit(), not $(document).ready()

The first thing you learn in jQuery is to call code inside the
$(document).ready() function so everything will execute as soon as the
DOM is loaded. However, in jQuery Mobile, Ajax is used to load the
contents of each page into the DOM as you navigate, and the DOM ready
handler only executes for the first page. To execute code whenever a
new page is loaded and created, you can bind to the pageinit event.
This event is explained in detail at the bottom of this page.

Also jQM only supports jQuery 1.6.4

I would use the live() like this

$('div').live('pageshow',function(event, ui) {
    alert($("#test").width());  
});

• http://jsfiddle.net/rCKzs/1/