Using the following code I managed to successfully read the width and height properties in FireFox 2/3, IE 6/7, Windows Safari 3/4 and Google Chrome, but the dimensions were not available in Opera (10).

$('')
	.load(function() {
		$('body').append(this);
		var w = this.width;
		var h = this.height;
		//..
	})
	.error(function() {
		//..
	})
	.attr('src', '/path/to/image.jpg');

After a fair bit of time playing around trying to debug this small snippet of code, I eventually discovered that if the image was appended to the DOM after the width and height had been read then Opera would report the values correctly.

		var w = this.width;
		var h = this.height;
		$('body').append(this);
		//..

Simply moving line 3 down to below the reading of dimensions solved this issue.

$("#id").css({opacity: 0.8});

It turns out that the latest version of jQuery (1.3.1) doesn’t believe that Opera 9.2 supports CSS opacity, and therefore it is ignored completely.

There are two possible fixes for this, the first is to simply upgrade Opera to a newer version (the latest is 9.6.3).

The second option is to tell jQuery that opera does support opacity using the following – or similar – within your script:

if ($.browser.opera) {
    $.support.opacity = true;
}

I tend to stick to Firefox as my development browser to test a project as I go along, this way I can almost guarantee that the layout will look fine when browsing in Opera, Safari (Win) and even IE7/8.

Internet Explorer 6 on the other hand is a whole different ball game altogether, even in standards compliance mode things can take an age to get sorted, often finding yourself floating elements as well as adding in any filters as it is unable to render png transparency or opacity correctly.

At least Microsoft had got the majority of things right when they released Internet Explorer 7 and now with the beta release of IE8 with the IE7 rendering engine option things are looking up for web developers.

Unfortunately we will have to put up with the woes of IE6 and below, at least until the percentage of users drops to a more insignificant amount. Currently around 30% of users are still browsing using IE6 which is enough to put doubt into every developers mind as to whether or not they should bother with it.

Currently I have Firefox 2 / 3 beta, Opera 9, Safari (Windows) and IE 8 (with built in 7 rendering option) all installed on my PC. Both Opera and Firefox allow for multiple installs of different releases on a single machine, but when it comes to IE6 I’ve had to either use the stand alone version or use a Virtual Machine with an XP and IE6 Image.

The stand alone version from Evolt is fine up until the point where you are wanting to test any filters, css conditional statements or set up a proxy connection.

The the virtual machine option on the other hand will render everything as expected, but does require you to go through the booting up process and download the latest image every couple of months as they expire.

With my irritations of backward compatibility aside, I believe as developers we should all continue to dedicate some of our time allowing as many people as possibly to have the same browsing experience, even though it can be a major chore at times and testing in each browser can have it difficulties.