JavaScript Where To ...
JavaScripts in the body section will be executed WHILE the page loads.
JavaScripts in the head section will be executed when CALLED.
Examples
Head section
Scripts that contain functions go in the head section of the document. Then we
can be sure that the script is loaded before the function is called.
Body section
Execute a script that is placed in the body section.
External script
How to access an external script.
Where to Put the JavaScript
JavaScripts in a page will be executed immediately while the page loads into the
browser. This is not always what we want. Sometimes we want to execute a script
when a page loads, other times when a user triggers an event.
Scripts in the head section: Scripts to be executed when they are
called, or when an event is triggered, go in the head section. When you place a
script in the head section, you will ensure that the script is loaded before
anyone uses it.
<html>
<head>
<script type="text/javascript">
....
</script>
</head>
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Scripts in the body section: Scripts to be executed when the page
loads go in the body section. When you place a script in the body section it
generates the content of the page.
<html>
<head>
</head>
<body>
<script type="text/javascript">
....
</script>
</body>
|
Scripts in both the body and the head section: You can place an
unlimited number of scripts in your document, so you can have scripts in both
the body and the head section.
<html>
<head>
<script type="text/javascript">
....
</script>
</head>
<body>
<script type="text/javascript">
....
</script>
</body>
|
Using an External JavaScript
Sometimes you might want to run the same JavaScript on several pages, without
having to write the same script on every page.
To simplify this, you can write a JavaScript in an external file. Save the
external JavaScript file with a .js file extension.
Note: The external script cannot contain the <script> tag!
To use the external script, point to the .js file in the "src" attribute
of the <script> tag:
<html>
<head>
<script src="xxx.js"></script>
</head>
<body>
</body>
</html>
|
Note: Remember to place the script exactly where you normally would
write the script!
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