Implement Enter key functionality to .js in Firefox Extension

Question

I'm trying to make it so when the user presses a button on a Firefox extension, the button triggers the same function as if the user pressed the Enter key.

The code is at http://github.com/cwill747/KioskKeyboard/blob/master/kioskkeyboard/content/overlay.js, that's where the whole project is, but I'll post it here too.

doEnter: function (){
        this.focus.value+='\r';
    },