Slide 15.3: JavaScript how to

Slide 15.2: JavaScript (cont.)
Slide 15.4: JavaScript where to
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JavaScript How to

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

Writing to the HTML Document
The example below writes a <p> element with current date information to the HTML document by using (i) the method write of the object document and (ii) the date function/object, which gives the current time.


<html> <body> <h4>My Web Page</h4> <script type="text/javascript"> document.write( "<p>" + Date( ) + "</p>" ); </script> </body> </html>

To insert a JavaScript into an HTML page, use the <script> tag. Inside the <script> tag, use the type attribute to define the scripting language. The <script type="text/javascript"> and </script> tells where the JavaScript starts & ends and are executed by the browser.

Changing HTML Elements
The example below writes the current date into an existing <p> element. To manipulate HTML elements, the example uses

the method getElementById of the object document and
the property innerHTML, which defines both the HTML code and the text that occurs between that element’s opening and closing tag. Each HTML element has an innerHTML property.


<html> <body> <h4>My Web Page</h4> <p id="demo">Current time</p> <script type="text/javascript"> document.getElementById("demo").innerHTML=Date(); </script> </body> </html>

Demonstration
The following demonstration shows how the script of HTML and JavaScript is displayed on the Web.


<html> <body> <script type="text/javascript"> document.write( "<h4>" + document.referrer + "</h4>" ) </script> </body> </html>

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