lyncd

March 2009 archive

Better Google Analytics JavaScript that doesn’t block page downloading

If you saw Steve Souders’ March 5 talk at Google and have ever used Google Analytics, then you were probably amused when he used GA’s JavaScript insertion code as his “wrong” counterexample. Well, at least I was, and somebody else mentioned it in the Q&A so I figure I’m not the only one.

The GA insertion code that Google gives you to put on your site does a couple of bad things: First, it uses document.write, and second, it loads ga.js directly, which blocks browsers from doing any page rendering or downloading of other page components (images, scripts, stylesheets) during the whole time it takes ga.js to download and execute. In other words, Google Analytics makes your pages load slower!

Using Steve’s best practices, I’ve coded up a better version that does DOM insertion of the script tag and uses the “script onload” technique to initialize the tracker, so that it doesn’t block I/O, and you can inline it anywhere on the page or even load it from an external file. You can choose to lazy-load GA whenever you want — for instance, even after window.onload fires — so that it’s totally asynchronous and doesn’t interfere with page rendering at all. more …

Filed under: Code.  Tagged: , , .

Optimize all your PNG and JPEG images with one command using imgopt

Here’s something useful for the web developers out there. It’s a script I’ve been using for a while that makes it super-easy to losslessly compress entire folders of PNG and JPEG files for the web.

If you’re familiar with PNG optimization, then you know about programs like advpng, optipng and pngout that optimize and recompress PNG files, making them much smaller than the likes of Photoshop can. My shell script combines all three of these utilities to achieve minimum file size, while hiding their command-line syntax and adding the ability to recursively process entire directory trees.

And, it works with JPEGs, too! It uses jpegtran (included with libjpeg) and another small utility I’ve included to optimize and strip all metadata from JPEG files. Since my script searches directories recursively, all you need to do is type, say, imgopt myproj/htdocs and it’ll take care of your entire website.

All compression is lossless, which means no pixels are changed and no information is lost, the files just get smaller — chances are your layout can shrink by as much as 50%, which is like getting free bandwidth, and it means your site will snap into place that much faster for users. more …

Filed under: Code.  Tagged: , , .

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