📄 js_whereto.asp
字号:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en-US" xml:lang="en-US" xmlns="http://www.w3.org/1999/xhtml">
<head><title>JavaScript Where To</title>
<link rel="shortcut icon" href="../favicon.ico" type="image/x-icon" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<meta name="Keywords" content="xml,tutorial,html,dhtml,css,xsl,xhtml,javascript,asp,ado,vbscript,dom,sql,colors,soap,php,authoring,programming,training,learning,beginner's guide,primer,lessons,school,howto,reference,examples,samples,source code,tags,demos,tips,links,FAQ,tag list,forms,frames,color table,w3c,cascading style sheets,active server pages,dynamic html,internet,database,development,Web building,Webmaster,html guide" />
<meta name="Description" content="Free HTML XHTML CSS JavaScript DHTML XML DOM XSL XSLT RSS AJAX ASP ADO PHP SQL tutorials, references, examples for web building." />
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="cache-control" content="no-cache" />
<link rel="stylesheet" type="text/css" href="../stdtheme.css" />
<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "../../https@ssl./default.htm" : "../../www./default.htm");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
var pageTracker = _gat._getTracker("UA-3855518-1");
pageTracker._initData();
pageTracker._trackPageview();
</script>
</head>
<body>
<a name="top"></a>
<table cellpadding="0" cellspacing="0" width="100%" bgcolor="#808080">
<tr>
<td width="234" valign="top">
<a href="../default.htm"><img src="../images/w3default80.jpg" border="0" alt="W3Schools" /></a>
</td>
<th valign="middle" align="left" class="right">
<iframe style="background-color:#808080" src="../banners/bannerframe.asp@adpartner=aspall2" height="90" width="728"
marginwidth="0" marginheight="0" frameborder="0" scrolling="no">
Your browser does not support inline frames or is currently configured not to display inline frames.
</iframe>
<br /></th>
</tr>
</table>
<table style="margin-left:1px" width="800px" border="0" cellpadding="0" cellspacing="2">
<tr>
<td width="137" class="content" valign="top"><br />
<a class="left" href="../default.asp" target="_top">
<img src="../images/homeicon.gif" border="0" alt="home" /></a>
<a class="left" href="../default.asp" target="_top">
<b>HOME</b></a>
<br /><br />
<b>JS Basic</b>
<br />
<a class="left" target="_top" href="default.asp" >JS HOME</a><br />
<a class="left" target="_top" href="js_intro.asp" >JS Introduction</a><br />
<a class="left" target="_top" href="js_howto.asp" >JS How To</a><br />
<a class="left" target="_top" href="js_whereto.asp" style='font-weight:bold;'>JS Where To</a><br />
<a class="left" target="_top" href="js_statements.asp" >JS Statements</a><br />
<a class="left" target="_top" href="js_comments.asp" >JS Comments</a><br />
<a class="left" target="_top" href="js_variables.asp" >JS Variables</a><br />
<a class="left" target="_top" href="js_operators.asp" >JS Operators</a><br />
<a class="left" target="_top" href="js_comparisons.asp" >JS Comparisons</a><br />
<a class="left" target="_top" href="js_if_else.asp" >JS If...Else</a><br />
<a class="left" target="_top" href="js_switch.asp" >JS Switch</a><br />
<a class="left" target="_top" href="js_popup.asp" >JS Popup Boxes</a><br />
<a class="left" target="_top" href="js_functions.asp" >JS Functions</a><br />
<a class="left" target="_top" href="js_loop_for.asp" >JS For Loop</a><br />
<a class="left" target="_top" href="js_loop_while.asp" >JS While Loop</a><br />
<a class="left" target="_top" href="js_break.asp" >JS Break Loops</a><br />
<a class="left" target="_top" href="js_loop_for_in.asp" >JS For...In</a><br />
<a class="left" target="_top" href="js_events.asp" >JS Events</a><br />
<a class="left" target="_top" href="js_try_catch.asp" >JS Try...Catch</a><br />
<a class="left" target="_top" href="js_throw.asp" >JS Throw</a><br />
<a class="left" target="_top" href="js_onerror.asp" >JS onerror</a><br />
<a class="left" target="_top" href="js_special_characters.asp" >JS Special Text</a><br />
<a class="left" target="_top" href="js_guidelines.asp" >JS Guidelines</a><br />
<br />
<b>JS Objects</b>
<br />
<a class="left" target="_top" href="js_obj_intro.asp" >JS Objects Intro</a><br />
<a class="left" target="_top" href="js_obj_string.asp" >JS String</a><br />
<a class="left" target="_top" href="js_obj_date.asp" >JS Date</a><br />
<a class="left" target="_top" href="js_obj_array.asp" >JS Array</a><br />
<a class="left" target="_top" href="js_obj_boolean.asp" >JS Boolean</a><br />
<a class="left" target="_top" href="js_obj_math.asp" >JS Math</a><br />
<a class="left" target="_top" href="js_obj_regexp.asp" >JS RegExp</a><br />
<a class="left" target="_top" href="js_obj_htmldom.asp" >JS HTML DOM</a><br />
<br />
<b>JS Advanced</b>
<br />
<a class="left" target="_top" href="js_browser.asp" >JS Browser</a><br />
<a class="left" target="_top" href="js_cookies.asp" >JS Cookies</a><br />
<a class="left" target="_top" href="js_form_validation.asp" >JS Validation</a><br />
<a class="left" target="_top" href="js_animation.asp" >JS Animation</a><br />
<a class="left" target="_top" href="js_image_maps.asp" >JS Image Maps</a><br />
<a class="left" target="_top" href="js_timing.asp" >JS Timing</a><br />
<a class="left" target="_top" href="js_objects.asp" >JS Create Object</a><br />
<a class="left" target="_top" href="js_summary.asp" >JS Summary</a><br />
<br />
<b>Examples/Quiz</b>
<br />
<a class="left" target="_top" href="js_examples.asp" >JS Examples</a><br />
<a class="left" target="_top" href="js_examples_2.asp" >JS Object Examples</a><br />
<a class="left" target="_top" href="js_examples_3.asp" >JS DOM Examples</a><br />
<a class="left" target="_top" href="js_quiz.asp" >JS Quiz</a><br />
<br />
<b>JS References</b>
<br />
<a class="left" target="_top" href="../jsref/default.asp" >JS Objects</a><br />
<a class="left" target="_top" href="../htmldom/dom_reference.asp" >JS HTML DOM</a><br />
<br />
<b>Selected Reading</b><br />
<a class="left" target="_top" href="../browsers/browsers_stats.asp">Web Statistics</a><br />
<a class="left" target="_top" href="../site/site_glossary.asp">Web Glossary</a><br />
<a class="left" target="_top" href="../hosting/default.asp">Web Hosting</a><br />
<a class="left" target="_top" href="../quality/default.asp">Web Quality</a><br /><br />
<a class="left" target="_top" href="../forum/default.asp">W3Schools Forum</a><br /><br />
<a class="left" target="_top" href="../about/about_helping.asp">Helping W3Schools</a><br /><br />
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*LeftLinkUnit*/
google_ad_slot = "4854527104";
google_ad_width = 120;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript"
src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td>
<td valign="top">
<table style="border: 1px solid gray" width="100%" bgcolor="#FFFFFF" border="0" cellpadding="5" cellspacing="0">
<tr>
<td>
<h1>JavaScript Where To ...</h1>
<a href="js_howto.asp"><img border="0" alt="previous" src="../images/btn_previous.gif" width="100" height="20" /></a>
<a href="js_statements.asp"><img border="0" alt="next" src="../images/btn_next.gif" width="100" height="20" /></a>
<hr />
<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>
<hr />
<a href="js_howto.asp"><img border="0" alt="previous" src="../images/btn_previous.gif" width="100" height="20" /></a>
<a href="js_statements.asp"><img border="0" alt="next" src="../images/btn_next.gif" width="100" height="20" /></a>
<br />
<hr />
<!-- **** SPOTLIGHTS 1 **** -->
<iframe src="../banners/aspallframe.asp" height="110" width="485"
marginwidth="0" marginheight="0" frameborder="0" scrolling="no">
Your browser does not support inline frames or is currently configured not to display inline frames.
</iframe>
<hr />
<!-- **** SPOTLIGHTS 2 **** -->
<h2>Want To Be A Web Master?</h2>
<p>If you want to be a Web Master, you will have to host your web site with an ISP (Internet Service Provider).</p>
<p>MaximumASP offers seven different configurations of dedicated servers to meet your Windows and .NET hosting needs.
Hosted on our multi-tiered Enterprise Class network, these servers provide the performance, security and reliability
you need to host your high end web sites and applications.
</p>
<p><a target="_blank" href="../../www.maximumasp.com/about/specials.aspx">Visit MaximumASP</a></p>
<hr />
<!-- **** SPOTLIGHTS 3 **** -->
<table cellpadding="0" cellspacing="0"><tr><td width="72"></td><td>
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*txt*/
google_ad_slot = "1699448869";
google_ad_width = 336;
google_ad_height = 280;
//-->
</script>
<script type="text/javascript"
src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td></tr></table>
<hr />
<center>
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*imgtxt*/
google_ad_slot = "8606855891";
google_ad_width = 468;
google_ad_height = 60;
//-->
</script>
<script type="text/javascript"
src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</center>
<hr />
<!-- **** END SPOTLIGHTS **** -->
</td></tr>
<tr><td>
<p>Jump to: <a href="#top" target="_top"><b>Top of Page</b></a>
or <a href="../default.asp" target="_top"><b>HOME</b></a> or
<a href='js_whereto.asp@output=print' target="_blank">
<img src="../images/print.gif" alt="Printer Friendly" border="0" />
<b>Printer friendly page</b></a></p>
<p>W3Schools provides material for training only. We do not warrant the correctness of its contents.
The risk from using it lies entirely with the user.
While using this site, you agree to have read and accepted our
<a href="../about/about_copyright.asp">terms of use</a> and
<a href="../about/about_privacy.asp">privacy policy</a>.
</p>
<p><a href="../about/about_copyright.asp">Copyright 1999-2008</a> by Refsnes Data. All Rights Reserved.</p>
<table border="0" width="100%" cellspacing="0" cellpadding="0"><tr>
<td width="60%" align="left">
<a href="../../validator.w3.org/check@uri=referer" target="_blank">
<img src="../images/vxhtml.gif" alt="Validate" width="88" height="31" border="0" /></a>
<a href="../../jigsaw.w3.org/css-validator/check@uri=referer" target="_blank">
<img src="../images/vcss.gif" alt="Validate" width="88" height="31" border="0" /></a>
<a href="../../www.w3.org/WAI/WCAG1A-Conformance" title="Explanation of Level A Conformance" target="_blank">
<img src="../images/wai.gif" alt="W3C-WAI level A conformance icon" width="88" height="31" border="0" /></a>
</td>
<td>
<a href="../xhtml/xhtml_howto.asp" target="_top">W3Schools was converted to XHTML in December 1999</a>
</td></tr>
</table>
</td></tr>
</table>
</td>
<td width="145" align="center" valign="top">
<iframe style="background-color:#f1f1f1" src="../banners/rightcolumn.asp@secid=js" height="1500" width="147"
marginwidth="0" marginheight="0" frameborder="0" scrolling="no">
</iframe>
</td>
</tr></table>
</body>
</html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -