How to keep mouse within a window?

I want to keep mouse within an area or within a window, can not move out, by javascript.
It is very appreciated if having some guides.
Thanks in advance

you cant do that, if they could, mouse could never even leave the browser your page was on to access other applications!

First, I want to change to mouse position. Is there a javascript to do that?

JavaScript can only read the current position of the mouse - it is not able to actually move the mouse.

You can move the web page using JavaScript so if you need the mouse over a specific spot in the page then you could move the page to put that spot under the mouse (as long as the mouse is still over the web page).

you cant do that, if they could, mouse could never even leave the browser your page was on to access other applications!
Or, more importantly, to close the browser.