Basics JavaScript

Basics JavaScript
By Sazilah Salam

Learning Outcome
At the end of this lesson, students should be
able to:
i) Insert JavaScripts in HTML documents
ii) Declare JavaScript variables in HTML
documents

JavaScript Syntax
• The HTML <script> tag is used to insert a JavaScript into an
HTML page.

The <script> tags tell
the browser to expect
a script in between
them.

<html>
<body>
<script type="text/javascript">
document.write("JavaScript is not Java");
</script>
</body>
This part that
</html>

writes/display the
actual text
3

Where to put your scripts?
1.
2.
3.
4.

Scripts in <head>
Scripts in <body>
In both the body and the head section
Using an External JavaScript

4

Where to put your scripts? <head>.
<html>
<head>
function message()
{
alert("This alert box was called with the onload event");
}
</script>
</head>

<body onload="message()">
</body>
</html>
5

Where to put your scripts? <body>.
<html>
<body>
document.write("JavaScript is not Java");
</script>
</body>
</html>
6

Where to put your scripts? <head> and <body>
• <html>
<head>
function message()
{
alert("This alert box was called with the onload event");
}
</script>
</head>
<body onload="message()">
document.write("This message is written by JavaScript");
</script>
</body>
</html>

7

Where to put your scripts? External javascript
• <html>
<head>
<script type="text/javascript" src="xxx.js"></script>
</head>
<body>
JavaScript external
</body>
file with a .js file
</html>
extension.

8

9

JAVASCRIPT VARIABLES
Rules for variable names:
• Variable names are case sensitive
• They must begin with a letter or the underscore character
• You can create a variable with the var statement:
var strname = some value

• You can also create a variable without the var statement:
strname = some value
•

Assign a Value to a Variable
var strname = "Hege"
Or like this:

strname = "Hege"

<html>
<body>
var firstname;
firstname=“Toot";
document.write(firstname);
document.write("<br />");
firstname=“Tweet";
document.write(firstname);
</script>

javascript variables
firstname=“Toot";

variable

value

<p>The script above declares a variable, assigns a value to it, displays
the value, changes the value, and displays the value again.</p>
</body>
</html>

Basics JavaScript

Recommended

Recommended

More Related Content

What's hot

What's hot (16)

Viewers also liked

Viewers also liked (16)

Similar to Basics JavaScript

Similar to Basics JavaScript (20)

Recently uploaded

Recently uploaded (20)

Basics JavaScript