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What is JavaScript?
· JavaScript is a scripting language
· A scripting language is a lightweight programming language
· A JavaScript is lines of executable computer code
· A JavaScript can be inserted into a HTML page
How does it work?
When a JavaScript is inserted into a HTML document, the Internet
browser will read the HTML and interpret the JavaScript. The
JavaScript can be executed immediately, or at a later event.
What can a JavaScript do?
JavaScript gives HTML designers a programming tool
HTML authors are normally not programmers, but since JavaScript
is a very light programming language with a very simple syntax,
almost anyone can start putting small "snippets" of code into
their HTML documents.
JavaScript can put dynamic text into a HTML page
A JavaScript like this: document.write("<h1>" + name + "</h1>")
can write variable text into the display of a HTML page, just
like the static HTML text: <h1>Bill Gates</h1> does.
JavaScript can react to events
A JavaScript can be set to execute when something happens, like
when a page has finished loading or when a user clicks on an
HTML element.
JavaScript can read and write HTML elements
A JavaScript can read an HTML element and change the content of
an HTML element.
JavaScript can be used to validate data
JavaScripts can be used to validate data in a form before it is
submitted to a server. This function is particularly well suited
to save the server from extra processing.
How to put a JavaScript into an HTML document
<html>
<head>
</head>
<body>
<script language="JavaScript">
document.write("Hello World!")
</script>
</body>
</html>
And it produces this output:
Hello World!
To insert a script in an HTML document, use the <script> tag.
Use the language attribute to define the scripting language.
<script language="JavaScript">
Then comes the JavaScript: In JavaScript the command for writing
some text on a page is document.write:
document.write("Hello World!")
The script ends:
</script>
Examples
1.How to write text on a page
Coding
<html>
<body>
<script language="JavaScript">
document.write("Hello World!")
</script>
</body>
</html>
Output
Hello World!
2.How to format the text on your page with HTML tags
Coding
<html>
<body>
<script language="JavaScript">
document.write("<h1>Hello World!</h1>")
</script>
</body>
</html>
Output
Hello World! |