This one works:
<input type="button" value="test" onclick="alert('hey'); alert('ho');" />
And this one too:
function Hey()
{
alert('hey');
}
function Ho()
{
alert('ho');
}
.
<input type="button" value="test" onclick="Hey(); Ho();" />
So the answer is – yes you can 🙂
However, I’d recommend to use unobtrusive JavaScript.. mixing js with HTML is just nasty.