The actual HTML structure of a collapsible in jQuery Mobile 1.0RC2 is the following (after the framework has made its pass on the HTML):
<div id="collapsePlace" data-content-theme="e" data-role="collapsible" class="ui-collapsible ui-collapsible-collapsed">
<h3 class="ui-collapsible-heading ui-collapsible-heading-collapsed">
<a class="ui-collapsible-heading-toggle ui-btn ui-btn-icon-left ui-corner-top ui-corner-bottom ui-btn-up-c" href="#" data-theme="c">
<span aria-hidden="true" class="ui-btn-inner ui-corner-top ui-corner-bottom">
<span class="ui-btn-text">Place:
<span class="ui-collapsible-heading-status"> click to expand contents</span>
</span>
<span class="ui-icon ui-icon-plus ui-icon-shadow"></span>
</span>
</a>
</h3>
<div class="ui-collapsible-content ui-body-e ui-collapsible-content-collapsed" aria-hidden="true">
<!--things...-->
</div>
</div>
The nested <span>
element within the <span class="ui-btn-text">
element makes this a little tricky. If you want to preserve the structure of the <span class="ui-btn-text">
element you will need to save the nested <span>
element, overwrite it, and then replace it:
//run code on document.ready
$(function () {
var num = 1;
//add click handler to link to increment the collapsible's header each click
$('a').bind('click', function () {
//cache the `<span class="ui-btn-text">` element and its child
var $btn_text = $('#collapsePlace').find('.ui-btn-text'),
$btn_child = $btn_text.find('.ui-collapsible-heading-status');
//overwrite the header text, then append its child to restore the previous structure
$btn_text.text('New String (' + num++ + ')').append($btn_child);
});
});
Here is a jsfiddle of the above solution: http://jsfiddle.net/jasper/4DAfn/2/