console.log is the best tool for debugging javascript. In Firefox Firebug and Chrome Dev Tools you can even log objects which are represented as tree nodes of properties. If Firebug or Dev Tools in Chrome and IE9 are not opened, all these messages are ignored. But IE8 doesn’t understand console (if Dev Tools are closed) and raises an error: To avoid these errors, just declare an empty function just for IE8–:

When you code, you can save a lot of time and nerves if you have good tools. Here are my favorites: Programmer’s notepad ULS Log Viewer Resharper t4toolbox HTML5 and CSS3 standards