0) What you do is not cross-browser.
1) Use jquery, forget plain javascript:
https://api.jquery.com/category/events/event-handler-attachment/[
^], more precisely the
bind[
^] method.
2) by adding round brackets (
= change1()
) you don't assign the function, you call the function and assign it's result. But this is not what you want.
3) Simply remove brackets:
= change1;