run and run javascript function (until onmouseover event,until one key of keyboard is down)

actually i have three kind of one question ( how to run and run javascript function)

1.how can i run and run a javascript function with onmouseover event of an html element until mouse move away ?

2.how 开发者_StackOverflow中文版can i run and run a javascript function until mouse left button is down? (onclick event)

3.how can i run and run a javascript function until one key of keyboard is down (pressed)?