Are you into development of scripts using JS and DOM? Do you do AJAXian scripting (using XMLHttp etc)? Then you might have realized the pain of not being able to debug them when faced with problems. A set of 'alert's is not always elegant.
So here's what you do:
1. First things first : Use Firefox
2. Install these extensions.
If you start using this, you will forget that you are using a browser. You will see how the browser is changing into something like an IDE. More about it here.
* Firebug : https://addons.mozilla.org/extensions/moreinfo.php?id=1843&application=firefox
This extension shows you errors that occur during rendering of a page. Click on the line no and it will transfer you to the appropriate line in the appropriate file. Not just this, you can also use this to inspect different values of the HTML DOM, by just clicking inspect element and then clicking the item that you want to inspect and find request/responses of XMLHttp Requests.
* Hypertext DOM browser : https://addons.mozilla.org/extensions/moreinfo.php?id=1584&application=firefox
Yet another cool extension that helps you view the DOM values. This is more 'navigable' than the one that Firebug provides. It also has an evaluator, which helps you to navigate to the appropriate node and then start inspecting the values.
HTML scripting has never been as much fun before!