Lazy loading is available in many instantiations. This post is less about lazy loading, and more about the prevalence of sites downloading more JS than used initially and the need for tools to help identify the split. As Nicholas says, the code dependencies might be too complex to separate. But some libraries, like YUI, are already modular. Also, an approach like Doloto that substitutes stub functions avoids undefined symbol errors, and simply downloads the full implementation later.

This rule, and others, would be great additions to YSlow. I’d love to work with the team at Yahoo! to make that happen. As for a framework, something that used a headless Firefox with xvfb and jssh would probably be the answer. If I get to it first I’ll post about it and make it available. If someone else has experience and can help with this please contact me.

Your book and continued work on web performance has been great and I really appreciate it.

I’m interested in profiling the top 100 or so ecommerce sites and I wanted to find out if you had come up with a way of recording the data out of YSlow/Firebug for analysis. Is there a way to record it out to excel or some format for later review?

Second, in your web 2.0 talk, you mentioned the issue with inline scripts after a css. Are you planning on adding these items to YSlow? Or if you can’t work on YSlow any longer, are you planning on making something similar that would check for these rules?

Thanks again for the great work for the community.

sounds intriguing. Could you post how you calculated the percentages above? Specifically, did you calculate this by hand or do you have an automated tool?

This metric could be an interesting addition to YSlow.

Thanks

http://www.two-birds.de

function onSomeUserAction(){
dojo.require(”my.module”);
dojo.addOnLoad(function(){
//Do something with my.module
});
}

The process is not as automated as something like Doloto, but it is a proven technique used in sites today, like webmail.aol.com.

Take a look at

http://www.dodeca.co.uk/aspectjs/

I have not yet tried it but it looks promising