Question

On_Load is being called twice in a page. After using Firebug I found that it requests

http://localhost/default.aspx

then it does another request to

http://localhost/default.aspx#ced3db

I search for "#ced3db" and found it in a <table> in the page. When I remove its background attribute, the problem disapears.

<table width="430" height="281" border="0" 
    background="#ced3db" cellpadding="0" cellspacing="0">

I used a style attribute to avoid requesting the page twice. But, I still need to know: why there are two requests being made? I would like to understand the root cause to avoid re-requesting a page, because it can make any website slower.

Edit: The question has nothing to do with inline styles vs. using CSS files. It is about avoiding unintentionally re-requesting the page for performance reasons.

Note: On_Load can be called twice for several reasons, See ASP.NET Page.OnLoad executes twice

• AutoEventWireUp is true and you override On_Load.
• A user control contains AutoEventWireUp with true. Did not try that.
• The page or master page contains <img src="#"> or <img src="">

Answer 1

I’m pretty sure the background attribute for a table element expects a URL of an image. (I don’t think it’s even a proper attribute for that element, or at least I’ve never seen it used. Might have browser-specific behavior.)

If that’s the case, then this kind of makes sense. At the end of the question you note:

• The page or master page contains <img src="#"> or <img src="">

So that seems to be what’s happening here. The browser is interpreting that color tag as a URL and making a request back to the server resource to try to fetch it, since a hash URL by itself defaults to the current page. In an anchor tag it would just move the focus to that tag on the page, but in a resource-reference tag (such as an img, but in this case an attribute on table which expects a URL) it has to make another request.

Update: A little Googling on the attribute turns up a number of pages similar to this one, which seem to indicate that it is expecting a URL.

Indeed, the table element doesn’t seem to officially have a background attribute. At least not in HTML 4 or HTML 5.