Christian Heilmann

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Archive for September, 2008

Image Optimization made easy with

Tuesday, September 30th, 2008

Dedication is a really nice thing. Esteemed Yahoo colleagues Stoyan Stefanov and Nicole Sullivan of the exceptional performance team are two people who are dedicated to making the web a faster place.

Both Nicole and Stoyan have been talking about performance of CSS, JavaScript, HTML and also image optimization. Images can be optimized in two ways: visually (what is the quality) and file size. The latter is quite a corker, though as image editing tools leave a lot of information in files that we don’t really need – EXIF information, to be precise. If you open an image in a hex editor you will find a lot of things that can be safely removed without a change in the image quality.

There are a lot of open source tools to optimize images that way – amost one for each image format. Working through all of them can be a drag. This is why Stoyan and Nicole took their knowledge, dedication and all of these tools and built one application that does all the optimizations for you in one go:

Smushit Screenshot

You can upload a bunch of images, give it a URL or use it as a Firefox extension or bookmarklet. Smushit will show you how many bytes you can save by removing cruft from the images and gives you all the images as a zip file to replace them on your site. How cool and easy is that?

Here’s a video of Stoyan and Nicole presenting at The Ajax Experience in Boston (sorry about the audio):

Useful tweets widget using Yahoo Pipes and some JavaScript

Sunday, September 28th, 2008

If you look on the right side of this blog (and you can see) and you have JavaScript enabled you’ll spy a little “Useful tweets” widget (list). This is done with Yahoo Pipes and some JavaScript. As people asked me how it is done, here goes:

The idea

I use twitter a lot. Some of what I write is very relevant to the blog here, some is not fit for publication and some is just personal. So publishing all the tweets here would have been disruptive, hence I tried to find a way to filter things down.

What I do is that I end every tweet that I want to show up here with a § symbol, thus giving me a handle to filter out the good ones.

Playing nice with twitter and not summoning the fail whale

As twitter is probably the most hit API out there I didn’t want to go through the API and all the authentication malarkey. Instead I am using the ATOM feed and pipes to get the information and to filter it down.

Yahoo pipes is still full of win when it comes to filtering, mashing and converting data, and the pipe in question that I am using is available here: Useful tweets pipe

It takes the atom feed of a twitter user of a certain ID, removes all tweets but the ones ending in a § and removes the user name of the output.

Using the pipe and displaying the content

In order to display the pipe all you need is a small JavaScript and the right HTML in your page (or in my case WordPress template):

<div id="mytweet" class="user-13567">
  <a href="">My useful twitter updates</a>
<script type="text/javascript"

The link means the thing still makes sense when JavaScript is not available and the script does the rest. One thing you need to do to show your useful tweets instead of mine is to change the class on the DIV! You get the number from your twitter page:

  • Go to your twitter page, f.e.:
  • Click the RSS link at the bottom
  • Check the URL of the feed, your ID is the number in between the slash and ‘.rss’, f.e.:

The JavaScript for display of the badge is no rocket science whatsoever:

var tweets = function(){
  var x = document.getElementById('mytweet');
    var twitterUserId = x.className.replace('user-','');
    var s = document.createElement('script');
    s.type = 'text/javascript';
    s.src = '' + 
    '_id=f7229d01b79e508d543fb84e8a0abb0d&_render=json' +
    '&id=' + twitterUserId + '&_callback=tweets.tweet';
  function tweet(data){
      if(data && data.value && data.value.items){
          if(typeof data.value.items.length !== 'undefined'){
            var ul = document.createElement('ul');
            var all = data.value.items.length;
            var end = all > 5 ? 5 : all;
            for(var i=0;i < end;i++){
              var now = data.value.items[i];
              var li = document.createElement('li');
              var a = document.createElement('a');
              a.href =;

  • We check if the element with the ID mytweet exists
  • We then extract the user ID from the class name and create a new JavaScript pointing to the JSON output of the pipe. This, once loaded, will call tweets.tweet() and send the data as JSON
  • The tweet() method checks if data was retrieved, creates a list of links and appends it to the DIV.

Hope this is useful to someone else, too.

Reading blinds – a bookmarklet to help me read easier

Wednesday, September 24th, 2008

I am now a proud user of a 24 inch monitor at work and I realized that when I read large texts, the amount of white on the screen starts to hurt my eyes. Therefore I’ve written a small bookmarklet to black out part of the screen on demand and have a link top left to show and hide the blinds that cover the rest of the content. The blinds are fixed position so that I can scroll the content behind them. I also add padding to the bottom of the document to have enough scrolling space.

Here’s a blog without reading blinds:

A blog without reading blinds

The same blog with reading blinds on:

A blog with reading blinds

The bookmarklet is hosted on my server, to install it simply drag the following link to your links toolbar: Reading Blinds

Scripting Enabled at @mediaAjax 2008

Monday, September 15th, 2008

I am right now at @media Ajax 2008 getting ready to go on stage to deliver my “Scripting Enabled” talk, explaining how the main issue about accessibility is that we just don’t talk enough to each other. Technology is never really the boundary we have with accessibility, it is that we don’t understand how people work and what technology is capable of.

Links in the presentation

Scripting Maintainability – my presentation at Fronteers Conference, Amsterdam

Saturday, September 13th, 2008

I just came back from the Fronteers conference in Amsterdam. I was part of a panel on JavaScript and gave this talk about using JavaScript in large and distributed teams. There’ll be a video available soon, and I will also do a more in-depth report. For now, here are the talk slides: