On Wed, Feb 23, 2011 at 2:12 PM, Tab Atkins Jr. <jackalm...@gmail.com> wrote: > I know that iframes don't stop the rest of the page from rendering > while they load. I can't recall off the top of my head whether they > delay the load event or not.
It seems yes: "When there is an active parser in the iframe, and when anything in the iframe is delaying the load event of the iframe's browsing context's active document, the iframe must delay the load event of its document." http://www.whatwg.org/specs/web-apps/current-work/multipage/the-iframe-element.html#the-iframe-element I don't think this is a huge problem, though. The key thing is that the page will continue to lay out before the ad has started loading, unlike with <script>. Which would work today too, even without sandbox. I'm not sure why ad providers don't generally use iframe instead of script. Whatever the reason is, it's a pain in the neck, and it would be great if we could fix it. > If they do, and this is a problem, you > can easily just set up a script which listens for the load event and > then sets the @src or @srcdoc of the iframe. That's not acceptable. It would mean that the ad content doesn't display until well after the page is fully loaded, which might take a few seconds. By that time, the user might have scrolled past the ad if it's a top banner, for instance. The ad shouldn't interfere with content loading, but its load shouldn't be delayed either. I don't know if delaying the load event is enough of an issue to bother fixing, though.
