LESSON 07 – ASSORTED TOPICS
THE ALERT FUNCTION
You can
use the built-in alert function to make a small window pop-up and display a
message. The user hits ok to make the
window disappear.
Example 1
The
following code displays a message using a script section in the body. So the message window appears immediately
after the webpage is loaded.
<html>
<body>
<script type="text/javascript">
alert("Hey there buddy!");
</script>
This is the normal webpage part.
</body>
</html>
Click here to see this in action.
Example 2
The
following code displays the message window only when a button is clicked.
<html>
<head>
<script type="text/javascript">
function sayHi()
{
alert("Hey
there buddy!");
}
</script>
</head>
<body>
This is the normal webpage part.
<form>
<input type="button" value="Click
me" onClick="sayHi()">
</form>
</body>
</html>
Click here to see this in action.
COMBINING CONDITIONS
AND
We
sometimes need to combine conditions inside one if statement and make sure that
both are true.
We do so using the AND operator.
In javascript, the AND operator is &&.
The
syntax for this is:
if
(condition1 && condition2) //you say: if condition1 and condition2 are
true
{
//execute this if both conditions are true
}
OR
Sometimes,
we need to check if one condition or the other is true. To do this, we use the OR operator. In javascript, the OR operator is ||.
The
syntax for this is:
if
(condition1 || condition2) //you say: if condition1 or condition2 is
true
{
//execute this if one condition is true
(or both conditions are true)
}