Here's a list of the common event handlers, that all popular browsers can deal with...
Event When it's triggered onAbort An image is stopped from loading because the user either hits Stop or leaves the page. onBlur An element, such as a window, frame, or form field, loses focus; that is, when the user clicks on something else. onClick The user clicks on the particular element. onChange The value of a form field changes, for example, when the user types in some data. onDblClick The user double-clicks on the particular element. onError A loading error happens, like a missing image. onFocus The user puts the focus on the target element, by clicking on it or tabbing to it. onKeyDown A key on the keyboard is pushed down, regardless of whether it's then held down or released. onKeyPress This event is repeatedly triggered as long as a key is held down. onKeyUp A key on the keyboard is released. onLoad The browser completely loads the page. onMouseDown A key on the mouse is pushed down, regardless of whether it's then held down or released. onMouseMove The mouse moves. onMouseOut The pointer moves out of the target area. onMouseOver The pointer moves over the target element. onMouseUp A key on the mouse is released. onReset The Reset button of a form is clicked. onResize A window or frame is resized by the user. onSelect The user highlights text in a form field. onSubmit A form is submitted. onUnload The user leaves the page.
java script is client side scripting....i.e there is no need to execute it in the server and reply it back to client..so the validation time and burden on server will reduce