Since Ajax applications are so popular we developers are always looking for better JavaScript tools. Well, jsLex is an eclipse plug-in that attempts to make it easier to improve JavaScript/Ajax performance.

Below is an excerpt from the jsLex site.

Why jsLex?

As Ajax is used for an increasing number of projects it is also being used in projects with larger and larger code base. When the code base of a project increases, chances are you will run into performance issues.

Working on the Apache XAP project and Nexaweb's Universal Client Framwework, which has a large code base it became apparent that hand injection of profiling code only worked so well. A new technique was needed to make it possible to capture a complete view of the performance of an Ajax application in a similar way to using jProfile for Java code.

jsLex is that tool!

  • Go to the features page for more information. Click Me!
  • Go to the screen shots page to view screen shots of the application. Click Me!

jsLex gives developers a complete picture of the performance issues with-in thier Ajax application. By auto injecting profiling code using jsLex ant task, developers don't need to modify their code to track down bottlenecks, minimizing coding erros and saving time.

Currently developers need to hand inject profiling code into their applicaiton. Though this can be easily done as in the example below. Such a technique offers limited information and requires the developer to know percisely where the problem is located. Otherwise developers need to modify their code over and over as the try to find the problem area(s).

function doLongTask(){
  var start = new Date(); 

  for (var index = 0; index < infinite; index++){
     //Do something here

  end = new Date(); 
  alert ("doLongTask took " + (end - start) + 
         " milliseconds to complete." );

You can read more about jsLex here.

I think that jsLex makes a good attempt of improving performance profiling of Ajax applications. Also, since the tool plugs-in to the extremely popular Eclipse IDE it can be very useful to many developers. If you have used jsLex, I would love to hear your experience with the plug-in.

The other important thing that jsLex does; it makes it very easy to bundle CSS and JavaScript files together and compress them with the YUICompressor. This features works similar to the way Eclipse does the compile of Java files. Select a group of JavaScript and create a bundle and then use the bundled and compressed file in your application reducing the number of requests.

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