January 2010
Intermediate to advanced
791 pages
14h 17m
English
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Chapter 24. HTML Tips and Tricks
IN THIS CHAPTER
Preloading Images
Stretching Title Bars
Controlling Text Breaks in Table Cells
Simulating Newspaper Columns
Including Image Size for Fast Display
Protecting E-mail Addresses
Automating Forms
Modifying the User Agent Environment
Throughout this book, you have read about the ins and outs of the various HTML tags and entities. This chapter covers a few tips and tricks you can use to supplement your HTML knowledge to achieve real-world results.
Preloading Images
One of the things that can really slow down the display of Web pages is an abundance of images, each of which can contain the equivalent of 17,000 to 20,000 characters.
A trick that was developed to help overcome the delays experienced while image-rich documents load is image preloading. Through the use of JavaScript, image files are loaded into image objects. The net result is that the graphics are not displayed but are loaded into the browser's cache for later use. When it is time for the browser to actually display the image(s), they are taken from the local cache instead of having to make the trip across the Internet.
The script embedded in the following document is an example of an image preload script:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>Preloading Images</title> <script type="text/JavaScript"> // Assign path of images to be preloaded to // array, one image per index
var imagenames = []; imagenames[0] = "images/header.gif"; ...
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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.