onMouseOver, onMouseOut Events
	onClick, onChange Events Handlers
	Using the onSubmit Event Handler

You commonly use onMouseOver event with anchor tags (<A>) to provide additional information about the link. The onMouseOut event, then, generally undoes what the onMouseOver event does. Using these event handlers, you can, among other things, implement timed status bar events, swap images, and alert visitors.

Example :

<A HREF= " http://www.layoutgalaxy.com/ " onMouseOver = "window.status
= 'Check us out!' " onMouseOut = "window.status=' '; return
true">Visit the Layout Galaxy site. </A>

You can use onClick and onChange handlers, which are activated when visitors click an object or a button or change a form field. Including these event handlers is similar to using the onMouseOver and onMouseOut event handlers.You can use the onChange or the onClick event handler to set link destinations in forms, among other things.

Example :

<IMG SRC= "infolink.jpg" onClick = "alert('Visit Layout Galaxy!'); return true">
// This gives users alert when they click on the image.
<SELECT NAME= "Activity" onChange= "setLink(this.selectedIndex)">.
           .
           .
           .
</SELECT>
// The onChange event handler passes information to a function called setLink. The selectedIndex property is the position in the list of the current selection in the list. So, this.selectedIndex is the numeric value that represents the position in the current list of the value selected.

One of the most common uses for the onSubmit event handler is to validate form input. You can verify that visitors fill in required fields, make required selection, or that they fill in an appropriate combination of fields.

Example :

Now you see an exmaple which sends an alert message to the user saying that he has not filled in required fields.

<SCRIPT language = "JavaScript">
<!--
function checkOut( ) {
for (x=0; x<document.survey.elements.length; x++) {
             if (document.survey.elements[x].value == " ") {
               alert("Sorry, you forgot one of the required fields. Please try again.");
                             break;    }
             }
             return false;
if (document.survey.firstname.value.length <=2) {
             alert("Please enter your full first name.")
             return false;   }
if (document.survey.emailaddr.value.indexOf('@') == -1 ) {
             alert("Please correct your email address. It should look like you@domain.com");
             return false;}
}
// - - >
</SCRIPT>