Javascript in the address bar

I have written few times about the little known features of variuos products etc. Today I will add one more to the list. There is a little known feature that web browsers have that can be very useful...

The feature I'm talking about is the possibility to execute simple (or even complex) Javascript code from the address bar. While reading this go ahead and type something like:

javascript: alert(2+2);

in your brwoser's address bar and hit enter. You will see a messagebox containing the result of the expression passed as the argument to the altert function. A simple calculator, but you can go and create more complex scripts such as scripts modifying some DOM elements.

Here is a script that I sometimes use to get the current DOM of the page - after it has been modified by any user actions/javascripts such as AJAX calls.

javascript: var x = window.open(); x.document.write(document.childNodes[1].innerHTML.replace(new RegExp(/</g), "&lt;").replace(new RegExp(/>/g), "&gt;"))

If the page you are trying to view does not have the DOCTYPE declaration just change the document.childNodes[1] to document.childNodes[0]. I have tested this with IE 6.0 and it seems to work well. For FireFox users there are a lots of plugins available to do the same thing.