> > > My understanding is we put script tags in the head so as to not > > > clutter up the body DOM. I don't think it has anything to do with > > > ready(), and I'm pretty sure ready() doesn't require > > > script tags to be in the head...
> > Yes, but if you put the scripts at the end of the body you don't need > > to use ready(), e.g. that is literally the same as using ready()... > So why don't we just always put script tags at the end of the body? > What's the disadvantage of that? One disadvantage is that it can lead to sloppy display behavior when the page loads. The browser will never start rendering a page while the HEAD is loading. But once it starts loading the BODY, the browser is free to render a partial page any time it feels like it. In practice, this doesn't usually happen unless something causes the page loading to stall. In particular, if there is a script tag that loads an external script, the browser is very likely to render the page using whatever it has available at that point. You can see this in action on any typical newspaper site such as www.mercurynews.com. Any time you navigate to a new page, stuff jumps around all over the place while the page loads. This is caused by the script tags that are sprinkled willy-nilly throughout the page. A script tag at the very end of the body is less likely to trigger this behavior, but it could still happen if the script modifies DOM elements earlier in the page. The browser reaches the script tag, and while it waits for the external script to load it decides to render what it has so far. Then the script loads and modifies the page, so things jump around when this happens. -Mike
