JavaScript Event Handlers

When your users visit your website, they do things like click on things, hover over things etc. These are examples of what JavaScript calls events. Using JavaScript, you can respond to an event using Event Handlers. You can attach an event handler to the HTML element for which you want to respond to when a specific event occurs. For example, you could attach JavaScript'sonMouseover event handler to a button and specify some JavaScript to run whenever this event occurs against that button.
The HTML 4 specification defines 18 event handlers as listed below:

Event Handler	Event that it handles
onBlur	User has left the focus of the object. For example, they clicked away from a text field that was previously selected.
onChange	User has changed the object, then attempts to leave that field (i.e. clicks elsewhere).
onClick	User clicked on the object.
onDblClick	User clicked twice on the object.
onFocus	User brought the focus to the object (i.e. clicked on it/tabbed to it)
onKeydown	A key was pressed over an element.
onKeyup	A key was released over an element.
onKeypress	A key was pressed over an element then released.
onLoad	The object has loaded.
onMousedown	The cursor moved over the object and mouse/pointing device was pressed down.
onMouseup	The mouse/pointing device was released after being pressed down.
onMouseover	The cursor moved over the object (i.e. user hovers the mouse over the object).
onMousemove	The cursor moved while hovering over an object.
onMouseout	The cursor moved off the object
onReset	User has reset a form.
onSelect	User selected some or all of the contents of the object. For example, the user selected some text within a text field.
onSubmit	User submitted a form.
onUnload	User left the window (i.e. user closes the browser window).