September 2007
Intermediate to advanced
170 pages
4h 24m
English
Content preview from High Performance Web SitesBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Combined Scripts and Stylesheets
JavaScript and CSS are used on most web sites today. Frontend engineers must choose whether to "inline" their JavaScript and CSS (i.e., embed it in the HTML document) or include it from external script and stylesheet files. In general, using external scripts and stylesheets is better for performance (this is discussed more in Chapter 10). However, if you follow the approach recommended by software engineers and modularize your code by breaking it into many small files, you decrease performance because each file results in an additional HTTP request.
Table 3-1 shows that 10 top web sites average six to seven scripts and one to two stylesheets on their home pages. These web sites were selected from http://www.alexa.com, as described in Chapter 1. Each of these sites requires an additional HTTP request if it's not cached in the user's browser. Similar to the benefits of image maps and CSS sprites, combining these separate files into one file reduces the number of HTTP requests and improves the end user response time.
Table 3-1. Number of scripts and stylesheets for 10 top sites
To be clear, I'm not suggesting combining scripts with stylesheets. Multiple scripts should be combined into a single script, ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.