|
The landscape of the internet has changed a great deal over the
years. Websites are no longer static and lifeless, they have become
dynamic and interactive. A consequence of this is that the size of
modern websites has increased significantly. This poses a couple of
important issues:
- It takes more time for webpages to be downloaded by client browsers.
- Average website bandwidth usage has increased.
Most internet surfers won't wait 30 seconds for a page to load in
its entirety, they'll simply move on to something else. Also, if you
own or manage an even moderately busy website you will know just how
much bandwidth is worth. It is a precious commodity that can increase
the figures on your monthly hosting bill. As a result of this, a lot of
emphasis is now being placed on website optimization.
Yahoo has published a set of rules
which outlines some of the methods that can be employed to make your
website as lean and fast as possible. One of the methods suggested is
to compress and minify
external CSS and JavaScript files. Some PHP frameworks employ some form
of optimization of these files and if you have control over your server
you can always install mod_gzip
which would handle compression of these files. If you are not using a
PHP framework or you use a shared hosting plan (most of which won't
allow you to use mod_gzip because it can be a CPU hog) then read on.
First off, we will create a .htaccess file in which we will put our rewrite rules:
IndexIgnore *
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteRule ^(.*\.((js)|(css)))$ optimizer.php?file=$1
</IfModule>
Place a copy of this file in your /js and your /css folders. The
first line really has nothing to with our optimization, all it does is
it prevents listing of the contents of the directory when someone
navigates to http://www.yourdomain.com/js or
http://www.yourdomain.com/css. Not necessary but good practice. The
next few lines redirects incoming requests to the file optimizer.php if
the file extension is .js or .css and passes the filename to it as a
query string. Next, we'll create a file called optimizer.php:
<?php
if(!isset($_GET['file'])) die('Invalid parameter!');
$file = file_get_contents($_GET['file']);
$file = preg_replace("/((?:\/\*(?:[^*]|(?:\*+[^*\/]))*\*+\/)|(?:\/\/.*))/", "", $file);
header("Expires: Fri, 21 Dec 2012 00:00:00 GMT");
header("Content-type: application/x-javascript");
ob_start("ob_gzhandler");
echo $file;
ob_flush();
flush();
?>This file should also be placed in both the /css and /js folders.
What this script does is it grabs the filename from the $_GET array,
reads the contents of the file into a variable, strips the file of all
comments, sends content type and expires headers
to the browser, compresses the contents of the variable (via output
buffering) and sends the optimized CSS or JavaScript back to the
browser. Simple and straightforward.
This method is a simple way to optimize your external .js and .css
files when you don't have access to better(?) methods. The only issue I
have noted so far with this method is that it will mess up the minified
version of the jQuery library which really isn't an issue since its
already minified. If you are using the minified version of jQuery on
your website simply use this code in your optimize.php file instead:
<?php
if(!isset($_GET['file'])) die('Invalid parameter!');
$file = file_get_contents($_GET['file']);
$jqueryFile = 'name_of_your-jquery_file';
if($file!=$jqueryFile) $file = preg_replace("/((?:\/\*(?:[^*]|(?:\*+[^*\/]))*\*+\/)|(?:\/\/.*))/", "", $file);
header("Expires: Fri, 21 Dec 2012 00:00:00 GMT");
header("Content-type: application/x-javascript");
ob_start("ob_gzhandler");
echo $file;
ob_flush();
flush();
?>Now go optimize your stylesheets and JavaScripts and make your users happier!
Footnote #1: This implementation will obviously only work on an apache server as a .htaccess file is used.
Footnote #2: The code used in this post is
simply a proof of concept. Little or no attention was paid to security.
In an actual implementation of this technique you would need to ensure
that this script is as secure as possible.
|