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Today is the Download Day for Firefox, which means the new release FF3 is out now. Go ahead, download and help set a Guiness record for the most software downloads in a day.

Also, last night we released a new YSlow version that works with FF3 and the latest Firebug 1.2 beta (and also FF2, FB1 and FB1.1). A download day indeed.

Oh, yeah, and I'm back in LA, California after a nice vacation in Bulgaria and Rome, having gained some weight as a result of all the feasts with family and friends

Always wanted to create a Firefox extension? Or a Firebug extension? Here's an easy way to take off the ground, no more excuses.

Firefox Extensions

The way most people get started with creating a Firefox extension is copying an existing extension and tweaking. This is not the best way as you can guess, the best way is to read documentation (where exists), but who cares about reading documentation. It's a fact that there are specific predefined files, directories and conventions you need to follow in order to get started with even the simplest "Hello World". Well, with my new tool, this is taken care of, so you can literally turn any piece of JavaScript (a bookmarklet for example) into a browser extension. Not bad, eh?

The tool

The tool is located at http://tools.w3clubs.com/ext/

It's basically just a simple form you fill out with your name, URL, extension name, etc, then a working extension is generated for you. You then install your own extension and just start modifying it. So your new extension is ready in under a minute.

Firebug extensions

I did this tool a while ago for personal needs and it has been working for me with no worries. Today before making it public, I thought of adding the option to generate Firebug extensions too. You knew Firebug is extensible and you can add new tabs, right? Yahoo!'s YSlow is an example of a Firebug extension.

I followed Honza's Firebug tutorials part I and II and it worked beautifully. Honza is a Firebug contributor and these tutorials are excellently written and highly recommended, even if you use my tool to generate the code, it's still a good idea to know why things are what/where they are.

So there you go, same tool for creating both Firefox and Firebug extensions.

Have fun with the tool, but be aware that writing extensions is addictive, don't say I didn't warn you. As always, any feedback is appreciated.

Steve Souders, performance architect at Yahoo, announced today the public release of YSlow.

What's YSlow?

It's an extension to Firebug (yes, correct, Firebug, not Firefox) that helps with performance optimization efforts. It scores your page on the scale A to F, based on compliance with Yahoo's performance rules. It's a tool that has been used internally at Yahoo and is now released to the world.

The score

Here's how YSlow scores Yahoo's homepage, gives it an A with 93 points out of 100

You can see on the screenshot how YSlow is just another panel within Firebug, and when you select the panel it gives you a few features. The main one is Performance (shown on the screenshot).

You get a list of 13 things YSlow has evaluated (they are based on the performance rule) and if you don't get an A, there is an arrow that gives you more explanations why. Every one of the 13 items on the list is linked to online documentation of the rule so you can figure out right then what could be improved.

Other features

Besides Performance, there's also the Stats tab which gives you comparison of how your page size for visitors coming with an empty cache vs the ones that have previously visited the page.

The other tab is Components which lists every component on the page along with some information, relevant to performance, such as if the component as gzipped, what was the ETag if any, component size and expiration date.

In the tools section you'll find a nice surprise - integration with the JSLint tool, the unforgiving JavaScript verifier by Douglas Crockford.

The score (revisited)

OK, I'm sure you'll find the tool invaluable, but you may frown upon the score. Well, the scoring system is made so that it suits Yahoo's purposes, but you can modify it so that it fits your specific needs. In order to customize the points system you can go about:config in Firebug and search for yslow. There you can specify points for the score. In addition to that you can find the file called yslowcontext.js in your Firefox extensions folder (should be somewhere in Documents and Settings/Application Data/Mozilla/extensions/steve@yahoo/, path abbreviated), if you can't find it, just search for it. In this file, there is an array that defines the weight of each of the 13 rules in the overall score, so you can tweak that as well. To find the array, search for lintweights

Have fun!

And happy performance tunning!

Links

• YSlow
• YSlow on Mozilla Add-ons
• Performance rules
• Performance research articles by Tenni
• … and my own phpBB optimization effort

Here are two bookmarklets that could make your life easier when trying to figure out why in IE a page behave as wrong as it behaves. For Firefox we have Firebug, so none of this is necessary. For IE we have also Firebug lite (see my post), but you need some setup before you can use it. With this thing here you can mess up any page you see on the web, not only yours

Bookmarklet 1 - Eval() textarea

I saw this bookmarklet here and it's beautiful. When you start it, it puts a textarea at the bottom of your page and you can type javascript in it, then eval()-uate it. Perfect! Only … it doesn't work in frames. So I did the same thing but when you have frames (works without frames as well). The way mine works is - you first select some text in a frame, then you click the bookmarklet. A new textarea, ready to execute javascript will be placed in this frame (or iframe) that you selected. Also in this case when you type document.something, it refers to the document in the frame, not the frameset.
If you don't select any text and click the bookmarklet, it will place the textarea in the topmost document, so it will work for frame-free pages as well.

So here's the bookmarklet.

And here's a page where you can test.

Bookmarklet 2 - dump anything

After having my beautiful textarea, I wanted to be able to dump variables, like print_r() or var_dump() but for Javascript. I googled and I found this little script. All I did then is to make it a bookmarklet. How it works? You select the bookmarklet, it gives you a prompt, where you type whatever you want to dump, like document.location for example. Then it shows you an alert with all properties of this thing you typed. (Don't try to dump document though, or something else that recurses, because the script won't handle the recursion and will freeze).

Install it from here:

While this second bookmarklet will most likely work in FF as well, you don't need it, you have firebug!

Let's say you want to quickly try out some small stylesheet changes, but you don't want to (or prefer not to, or for some reason temporarily you just can't) modify your application's CSS file(s). In FF it's easy - you have Firebug and you can play with styles until blue in the face. And in case you do get blue in the face and start making so many changes that you get lost, you can create a new clean and tidy CSS file, place it on your hard drive and use Web Developer extension to load it (Menu CSS->Add User Style Sheet). With WebDev Extension you can also Edit CSS right there, although unfortunatelly it's not always working when you have frames.

OK, there are options for Firefox. But how about IE?

In IE you have IE Developer Toolbar, definitelly helpful, but you can only modify element styles, not the stylesheet rules. So? A tiny little bookmarklet to the rescue!

My bookmarklet assumes you have a file called C:\user.css and loads this stylesheet on demand in your page, in every frame, just in case you use frames. Simple, yet useful, I hope. Here's the (readable) code:

javascript:
var css_file = prompt('Which CSS file you want to load today?','c:/user.css');
function addcss(w) {
    var html_doc = w.document.getElementsByTagName('head')[0];
    var css = w.document.createElement('link');
    css.setAttribute('rel', 'stylesheet');
    css.setAttribute('type', 'text/css');
    css.setAttribute('href', css_file);
    html_doc.appendChild(css);
}
var errors = 0;
function checkFrames(w) {
  if(w.frames && w.frames.length>0){
    for(var i=0;i<w.frames.length;i++){
      var fr=w.frames[i];
      try {
        addcss(fr);
      } catch (e) {
        errors++;
      }
      checkFrames(fr);
    }
  }
}
checkFrames(window);
addcss(window);
if (errors > 0) {
    alert('Could not access ' + errors + ' frame(s)');
}

To install and play around

Right-click this link and add it to your favourites:

Have in mind that this is IE-only (tested IE7). I don't think FF will allow you to access files on your local drive like this. But for FF you have the tools to do this anyway.

Another option to load local stylesheets in IE is to use the user CSS capability built in the browser, you can find it under Tools/Internet Options/Accessibility, but this will load your user CSS first (as opposed to last as the case is with my bookmarklet), so the "real" style definitions will overwrite yours, unless you always use !important and the "real" styles don't.

Thanks!

Have fun with the custom CSS and let me know how you find it.

Update: A better version of what I was trying to do is here. It works around the cross-domain permission problems in IE by not loading a page in the frame, but putting there the actual content.

Firebug - no words to describe how cool it is, really. After the recent new release (1.0. beta) the number of features is overwhelming. I for one can't live anymore without it, seriously.

One of the things I noticed on the website is the ability to use the Firebug console in other browsers than Firefox. I don't know if this existed before version 1.0 but if it did, it was the best kept secret. I am so addicted to the console in Firefox, I use it all the time to tweak a few things here and there when I'm working on a page. Recently I was looking for something similar for IE, but couldn't find it. Lo and behold, it was right under my nose.

So, here's the page that describes how to use Firebug in IE (and others). Basically you unzip the Firebug Lite files somewhere on your server and then you include firebug.js in your pages. But why stop there? And isn't it possible to avoid including this script on every page (and forgetting to remove once you're done, or removing it prematurelly since a page, just like a painting, is never really finished). Bookmarklets to the rescue!

I wanted to host the Firebug files on my hard-drive and then use a javascript dynamic include to load firebug.js via a bookmarklet. This way I would be able to load the firebug console every time I want it, on any page. Unfortunatelly IE's security policy won't allow it. Then?

Solution

The solution I came up with is:

1. you copy the Firebug Lite files somewhere on your server
2. you call a bookmarklet that will load firebug.js
3. you hit F12 and you have a console!

This procedure has to be repeated for every domain you're working on, because of the security policy that won't allow cross-domain frame scripting. You can have one copy for your http://localhost and one for every domain. To ease the creation of bookmarklets that load firebug.js, I came up with a Firebug bookmarklet generator.

In action

1. I copied Firebug Lite files (get the .zip) on this server (phpied.com), they are here.
2. I (and you can try the same) generate a bookmarklet, using the bookmarklet tool
3. Add the generated bookmarklet to the favorites
4. Go to any page on phpied.com
5. Click the new favorite
6. Hit F12 to show/hide the console

Here's how (a readable version of) the generated code looks like:

javascript:(function(){
  var firebug_js = document.createElement('script');
  firebug_js.setAttribute('type', 'text/javascript');
  firebug_js.src = 'http%3A//www.phpied.com/files/firebug/firebug.js';
  document.getElementsByTagName('head')[0].appendChild(firebug_js);
  firebug_js.onreadystatechange = function () {
    if (firebug_js.readyState == 'complete') {
      console.open()
    }
  }
})()

Minor improvement to the console

The Firebug Lite console executes the code you type, but doesn't show it again when you use the up/down arrows, the way it does in Firefox. So I added this feature (copying from myself), you can replace the firebug.js you download with my version.

Not sold yet?

Here's a screenshot of the console in action, I used it to change my photo on the homepage.

Go ahead, please

I strongly encourage everyone to try this out. Firebug is a beautiful thing and using even a bit of it in IE is great.