xulconsole.mozdev.org
mozdev.org - xulconsole: indexThursday January 12th 2017. Do you want fries with that project? Start a Project…. XUL Console is a Mozilla/Firefox extension. To ease the XUL developer work. Even if you're an expert in XUL coding, you sometimes need to quickly verify some code construction. And if you're a newbie, you'll probably find XUL Console very handy to try some examples and soon become a XUL Guru. At any time, you can evaluate the XUL code you typed in an have an immediate result of the evaluation displayed in the Output panel.
http://xulconsole.mozdev.org/