I'm trying to use the mozrepl Firefox extension to give me a Javascript REPL from within emacs. I think I've got it set up correctly. I can interact with the REPL from emacs and can explore the document pretty much as described in the tutorial pages. The problem comes when I try to do something really simple, like get a context to a canvas element: repl> document.getElementById("mycanvas").getContext("2d") !!! TypeError: document.getElementById("mycanvas") is null Details: message: document.getElementById("mycanvas") is null fileName: chrome://mozrepl/content/repl.js -> file:///C:/Users/teamonkey/AppData/Roaming/Mozilla/Firefox/Profiles/chfdenuz.default/mozrepl.tmp.js lineNumber: 1 stack: @chrome://mozrepl/content/repl.js -> file:///C:/Users/teamonkey/AppData/Roaming/Mozilla/Firefox/Profiles/chfdenuz.default/mozrepl.tmp.js:1 name: TypeError It's not just that particular instance: any call to getElementById will just return null. If I start up firebug I can enter the same thing and it will return a valid context, but I'd really like to get the REPL working in emacs. I don't think this is a bug but I've probably not configured mozrepl correctly. Can anyone help? Mozrepl 1.0, Firefox 3.6