JavaScript Logging

If you spend much time working with JavaScript, there will eventually come a day when you need to know the value of a variable (or an object’s field) as the execution of the script progresses, or why a script terminates unexpectedly. In simple scripts, you can accomplish this with JavaScript’s alert() function, which instructs the browser to create a dialog box with the argument set as the box’s caption. The message can be anything that helps you understand your script’s operation.

A nice article abt the javascript logging is avilable at A List Apart