[jQuery] How to loop iterate through a string of div elements

[Morgan]

Hey, I was wondering how I would be able to convert a string of html
into a series of div elements that I can iterate through and perform
jquery functions on, specifically .hide() and .slideDown().

For example, I retrieve a string from a jquery ajax call of html that
looks something like this,

<div class="post" id="post2918">
     <div class="header">
         Some Text
     </div>
     <div class="footer">
         Some other text
     </div>
</div>
<div class="post" id="post3978">
     <div class="header">
         Some other Text 2
     </div>
     <div class="footer">
         Some other text 2
     </div>
</div>

I want to inject onto the top of a much larger list of post elements
that all have the same class (so I cant just do a search by class).
When I inject them I need to be able to .hide() then .slideDown() each
element individually. I got it working for one element, but it seems
that when there are multiple posts in the returned ajax it gives me
the following error.

uncaught exception: [Exception... "Could not convert JavaScript
argument arg 0 [nsIDOMViewCSS.getComputedStyle]" nsresult: "0x80570009
(NS_ERROR_XPC_BAD_CONVERT_JS)" location: "JS frame ::
http://localhost:8080/js/jquery-latest.js :: anonymous :: line 871"
data: no]

So I think I need to somehow traverse through the list of returned
post elements, and perform a .hide() and a .slideDown() on them each
individually. Any help would be appreciated. Thanks.