I use Firebug\'s console.log() for debugging my website. If I try viewing my website in browsers without Firebug then I get a console is not defined er
The solution of @OcuS is sure the best, but you can enhance it with mine: Check this way to log to FF Console: Log to Firefox Error Console from JavaScript
Then add to the firebugx.js this 3 lines inside IF:
window.console['error'] = li
window.console['warn'] = li
window.console['debug'] = li
So you will see the log of every console error, warn and debug even when the Firebug is closed