loading javascript file accordingly

loading javascript file accordingly

I am trying to load from different javascript (.js) file accordingly. e.g.
when button 1 click, then load 1.js, when other one click, then load the
relevant .js file. (e.g. 2.js)
I've just know would be the usual way to load a js file. is there any
other way could achieve that with the same effect but provide the
possibilities to load different .js accordingly?? any jquery function
would also do that?
Reagrds