Test onclick & addEventListener_javascript tips for event binding

After going back last night, I discussed with Lei Zi how to "detect" events listening functions bound to an element on the page. The first thought was to start with a browser, such as FF, or Chrome and other development tools should have corresponding functions, so test:
Premise: it is only a simple small test, and addEventListener is a standard binding function. IE is incompatible with this function (IE corresponds to attachEvent). Therefore, this test first discards IE and uses Firefox 5.0.1, chrome 14.0, Opera 11.50
Test page:

The Code is as follows:

Test

TEST1

TEST2

TEST3