HTML Scripts
Add scripts to HTML pages to make them more dynamic and interactive.
Insert a Script into HTML Page
A script in HTML is defined with the <script> tag. Note that you will have to use the type attribute to specify the scripting language.
<html> <head> </head> <body> <script type="text/javascript">
document.write("Hello World!")
</script>
</body> </html> |
The script above will produce this output:
Hello World!
How to Handle Older Browsers
A browser that does not recognize the <script> tag at all, will display the <script> tag’s content as text on the page. To prevent the browser from doing this, you should hide the script in comment tags. An old browser (that does not recognize the <script> tag) will ignore the comment and it will not write the tag’s content on the page, while a new browser will understand that the script should be executed, even if it is surrounded by comment tags.
Example
| JavaScript: <script type=”text/javascript”> <!– document.write(”Hello World!”) //–> </script>VBScript: <script type=”text/vbscript”> <!– document.write(”Hello World!”) ‘–> </script> |
The <noscript> Tag
In addition to hiding the script inside a comment, you can also add a <noscript> tag.
The <noscript> tag is used to define an alternate text if a script is NOT executed. This tag is used for browsers that recognize the <script> tag, but do not support the script inside, so these browsers will display the text inside the <noscript> tag instead. However, if a browser supports the script inside the <script> tag it will ignore the <noscript> tag.
Example
| JavaScript: <script type=”text/javascript”> <!– document.write(”Hello World!”) //–> </script> <noscript>Your browser does not support JavaScript!</noscript>VBScript: <script type=”text/vbscript”> <!– document.write(”Hello World!”) ‘–> </script> <noscript>Your browser does not support VBScript!</noscript> |
Script Tags
| Tag | Description |
|---|---|
| <script> | Defines a script |
| <noscript> | Defines an alternate text if the script is not executed |
| <object> | Defines an embedded object |
| <param> | Defines run-time settings (parameters) for an object |
| <applet> | Deprecated. Use <object> instead |