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<p>From <b>http://www.w3schools.com</b> (Copyright Refsnes Data)</p>
<h1>JavaScript Where To ...</h1>
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<p class="intro">JavaScripts in the body section will be executed WHILE the page loads.</p>
<p class="intro">JavaScripts in the head section will be executed when CALLED.</p>
<hr />
<h2>Examples</h2>
<p><a target="_blank" href="tryit.asp@filename=tryjs_headsection">Head section</a><br />
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.</p>
<p><a target="_blank" href="tryit.asp@filename=tryjs_bodysection">Body section</a><br />
Execute a script that is placed in the body section.</p>
<p><a target="_blank" href="tryit.asp@filename=tryjs_externalexample">External script</a><br />
How to access an external script.</p>
<hr />
<h2>Where to Put the JavaScript</h2>
<p>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.</p>
<p><b>Scripts in the head section:</b> 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. </p>
<table width="100%" border="1" class="ex" cellspacing="0"><tr><td>
<pre><html>
<head>
<span class="insert"><script type="text/javascript">
....
</script></span>
</head></pre>
</td></tr></table>
<p><b>Scripts in the body section:</b> 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.</p>
<table width="100%" border="1" class="ex" cellspacing="0"><tr><td>
<pre><html>
<head>
</head>
<body>
<span class="insert"><script type="text/javascript">
....
</script></span>
</body></pre>
</td></tr></table>
<p><b>Scripts in both the body and the head section:</b> You can place an
unlimited number of scripts in your document, so you can have scripts in both
the body and the head section.</p>
<table width="100%" border="1" class="ex" cellspacing="0"><tr><td>
<pre><html>
<head>
<span class="insert"><script type="text/javascript">
....
</script></span>
</head>
<body>
<span class="insert"><script type="text/javascript">
....
</script></span>
</body></pre>
</td></tr></table>
<br />
<hr />
<h2>Using an External JavaScript</h2>
<p>Sometimes you might want to run the same JavaScript on several pages, without
having to write the same script on every page.</p>
<p>To simplify this, you can write a JavaScript in an external file. Save the
external JavaScript file with a .js file extension.</p>
<p><b>Note:</b> The external script cannot contain the <script> tag!</p>
<p>To use the external script, point to the .js file in the "src" attribute
of the <script> tag:</p>
<table class="ex" cellspacing="0" border="1" width="100%"><tr><td>
<pre><html>
<head>
<span class="insert"><script src="xxx.js"></script></span>
</head>
<body>
</body>
</html></pre>
</td></tr></table>
<p><b>Note:</b> Remember to place the script exactly where you normally would
write the script!</p>
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