Get javascript loaded content

Let's say I have a button on a page, if clicked it adds a div popup.

How can I access the div's content through JavaScript? Is this possible? I've tried searching the page with jQuery selectors but I did not find the div popup.

I have a bookmarklet that is similar to what follows:

javascript:(function() {
    alert($('newDivId').val());
})();

...suppose that newDivId is the id of the newly created div, if I execute that code by clicking on the bookmarklet I get an error 开发者_StackOverflowsaying that val() cannot be invoked on a null object.

I do not have access to the page source; do you have any suggestion?

$('#id_of_div').html()

OR

$('.class_of_div').html()

OR

$('#id_of_div_parent div').html()

ETC.

If that doesn't work, you might be trying to select it before it has been full inserted into the DOM. Be sure it's fully loaded before you try to access it.