Reduce HTTP requests or not?

Question

A theoretical question:
We all know about the pro\'s of minifying and combining javascript files in order to reduce HTTP requests to speed up a website. But when popular jav

Answer 1

I think it comes down to a couple of things:

1. How many pages use the code throughout your site
2. The quality of the CDN
3. How much code it is

There's also a difference between using popular Javascript packages, such as jQuery, and using a personal package, which only visitors who have visited your site will have.

The performance enhancement may occur from two places: 1) browser cache and 2) dns cache, which even if the file isn't stored locally, the dns server has a route that minimizes the request time, or even temporarily serves the file.

I would advise using a CDN and hosting the files locally. Depending on your resources (hardware/bandwidth), you might need to use a CDN anyhow. It'd be nice to use server side schedulers to check on the CDN status and reroute the path when applicable.

Also, take a reminder that some users choose to turn off their browser cache. So minifying your JS is always a plus. You should separate your JS into two files: 1) Needed on Load and 2) Not needed on load. Basically, get the necessary code out there first, to improve the perceived load time. Then load all the other extras (eg slideshows, color changers, etc).

One last point is to make use of the Expires headers, since none of this is important if you don't optimize that. That is what will really reduce the speed for returned visitors with cache enabled. YSlow is a nice Firefox addon that will help evaluate your load performance.

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To answer your question: Reduce HTTP requests, but do your own evaluation on the file size of the JS.

(Being Extreme) You don't want one 10MB JS file, or your site will take too long to load. Nor do you want 1000 10KB files, because of the HTTP overhead. Again, use this to illustrate the point that you want a balance between size and number of files - and as I said earlier, package them into performance needed vs wanted.