Q:

How do I use jquery's prop() to set the attribute of a checkbox? 

I want to use prop() to set the attribute of a checkbox to checked.  
When I use prop("checked",true) I can visually see that the checkbox is checked, but if I look at the HTML there is no attribute value called checked.  
For example:
<input type="checkbox" class="my_class" checked>

is what I would expect to see after using prop("checked", true).  
However, I don't see any change in the HTML code.  I want to later reference whether or not the attribute checked is set, but since there is not attribute called checked in the HTML, then I'm unable to reference it. 

A:

When using prop() you are changing the property and not the attribute, so the changes can't be seen in a DOM inspector, but it is for all intents and purposes changed. 
To later see if the element is checked, you'd do:
$('.my_class').is(':checked')

which would return true when checked or false when unchecked, regardless of what you might see in a DOM inspector.