To open the IE developer tools, simply press F12
The console log command is simply:
So for example:
This is a rudimentary example, but s is especially useful if you want to know the value of many variables at a glance (rather than keep having to press OK for each alert()!)
Watch out for...
Of course using breakpoints and stepping through the debugging, is more often a better option (I'll do a quick post on how to do this at a later date), but in many situations outputting to the console is very useful.
The IE developer tool bar is built into Internet Explorer 7+ (I pressume it will also be in IE9+). As mentioned above you can access it by pressing F12 (or by using the menu).
There are many variations of console.log, more information available on the MSDN site: Using Console for Logging Alerts and Error Messages
These posts are only here to give you quick and easy tips... however if web development is your day to day role, I'd highly recommend getting familiar with the built-in IE developer tools. More information is available on the MSDN site: IE Developer Tools tutorials