This is a Javscript bookmarklet. This shell really helps in trying to debug runtime values.
I did not write this! Source:
http://www.squarefree.com/shell/(This is a very long line! Create a new bookmark and paste this as the target url. Will not work for explorer but great in firefox.)
javascript:with(window.open("","_blank","width="+screen.width*.6+",left="+screen.width*.35+",height="+screen.height*.9+",resizable,scrollbars=yes")){document.write("\n\n\n\n\nJavaScript%20Shell%201.4\n\n\n\n\n\n\n\n\n\n\n\n\nJavaScript%20Shell%201.4
Features:%20autocompletion%20of%20property%20names%20with%20Tab,%20multiline%20input%20with%20Shift+Enter,%20input%20history%20with%20(Ctrl+)%20Up/Down,%20
Math,%20
help \n\n\n\n\n\n");document.close();}void%200