HTML and CSS Reference
In-Depth Information
The JavaScript program starts here in the head of the document. The function is
defined within the head of the document to guarantee that it will be defined be-
fore being called.
2, 3
The function greetings() is defined. It is very simple. It causes the background col-
or of the document to be a light blue color and causes an alert box to appear with
a greeting message.
The href attribute of the link tag is assigned a string consisting of the JavaScript:
pseudoprotocol, followed by the name of the function to be called. When the user
clicks this link, JavaScript calls the function, greetings() . (See Figure 7.5.)
Figure 7.5 After clicking the link, the function is called, causing the alert dialog box
to appear.
Calling a Function from an Event. An event is triggered when a user performs
some action, like clicking a button or moving the mouse over a link. The function
assigned to the event is called an event handler. When the event is triggered, the func-
tion is called. In the following example, when the user clicks the Welcome button, the
function is called.
<head><title>Functions and Events</title>
<script type="text/javascript">
function greetings(you){ // Function definition
alert("Greetings and Salutations! " + you);
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