MozRepl
enables you to directly
evaluate JS code written in Emacs in Mozilla — without any
reloading.
From the README:
This extension lets you write Javascript code in Emacs and
have it evaluated in a running Mozilla immediately. You will
be able to:
- Send lines of code from an interaction buffer.
- Send regions of code from Javascript sources.
-
Send the block the cursor is in (a function or other
brace-delimited area) from Javascript sources.
via the XUL
Weblog.