JavaScript - how Greasemonkey works

Question

I read " Dive into Greasemonkey " (by Mark Pilgrim ) written in 2005. It mentions that Greasemonkey wraps a user script in an anonymous function wrapper. Does Greasemonkey insert the wrapper into the source JavaScript code or add it as any event handler such as window.onload ?

Answer 1

Does Greasemonkey insert the wrapper into the source JavaScript code or add it as any event handler such as window.onload?

GM listens to DOMContentLoaded event (basically DOM Ready) here . Then wraps the userscript code and inserts that into a sandbox, here .