Missing radix parameter

This message is given by JSLint when you are using parseInt() without the second parameter radix. This might cause a problem when the variable passed to parseInt() starts with a 0, which makes JavaScript interpret the value as an octal number. Or if the string even starts with “0x” parseInt() might come up with the idea to see a hexadecimal number.

>>> parseInt("8")
8
>>> parseInt("08")
0
>>> parseInt("010") // A juicy mistake, octal numbers.
8
>>> parseInt("0x10") // Probably rare, but possible, hexadecimals.
16
>>> parseInt("08", 10) // Prevent problems, use the radix.
8
>>> parseInt("010", 10)
10

And if the paramter passed to parseInt() is a variable that comes from some other place you can not be sure that the string does not start with a “0″. So using the radix might save a lot of headache.

Handle global variables in JavaScript

When people write decent JavaScript (read: when they use JavaScript frameworks like jQuery which handle the quirks of JavaScript for them) they will often assume that certain top level variables are there, without explicitly defining it.

e.g.: $("#test").html("test");

This line is assuming that jQuery has been loaded and that the $ object is defined. If jQuery isn't loaded, the code will fail and claim that $ is undefined. Because of this, the JSLint validator will complain when validating this code and will state the following:

Implied global: $ 1

Problem at line 1 character 1: '$' is not defined.

(Note that this will also happen when we call a function that hasn't been defined yet inside a function. Sometimes it's impossible to avoid this.)

This can and should be fixed by adding this to the top of the document:

/*global $ */

Inside this global statement we can define all of the top level variables we expect there to be. This will tell JSLint that it should assume those variables are defined (or will be defined in time), and it will no longer complain. It also a very nice way of documenting which files and frameworks we need to run a certain JavaScript file, so it's a win-win again.

MyCamTools, UXI, Sakai 3 and other Sakai’s

A lot has happened in the world of (client side) development for Sakai over the last year. In fact, so much has happened that I haven’t been able to keep up with this blog.

We have managed to get MyCamTools out of the door and it has now been running in production at Cambridge for almost a year now. Reactions have been positive and we have had relatively few reported problems.

In August, we have started working on the UX Improvement project, based on designs made by Nathan Pearson, aimed at improving the Sakai 2.x UX. We have also introduced some Sakai 3 concepts into those screens. You can check the work at http://mycamtools.caret.cam.ac.uk .
I would like to thank Michigan, Indiana, Berkeley and Georgia Tech for their implementation help.

In March, we have started working on Sakai 3 RC 1, which would be a first step towards Sakai 3, and we’re hoping to bring into production this year.  A lot is going on, and it’s a fast moving target right now, so the best way to track the progress is to follow the dev server at http://131.111.21.17:9090/dev/ .

All of this might make more sense if you read through the presentation I recently gave at EuroSakai 2009 in Stockholm which you can find at SakaiEurope-Sakai3.pdf

Enabling JSLint in Aptana Studio

JSLint (http://www.jslint.com) is a pretty cool tool that allows you to validate your javascript code and find common bugs, style issues and pitfalls. Until recently, I was pasting my javascript code into JSLint from time to time, fixing some of the issues and then pasting it back into JSLint, ...

I have now however found a way of enabling the JSLint Validator inside Aptana Studio, which is the IDE in which I write all of my JavaScript code.

You can enable it by doing:

- Open Aptana Studio- Go to Window > Preferences
- Go to Aptana > Editors > JavaScript > Validation in the left hand menu
- Check "JSLint JavaScript Validator"- Hit OK- Go to Window > Show View > Validation
- You'll see the Validation on the bottom right of the screen- Now also click Toggle Information and Toggle Warnings (found on the top left corner of the validation pane)
- You're all set. JSLint will warn you whilst writing code

This is super useful, because I can now track JSLint issues while I'm writing the code, which should improve productivity!