📄 js_try_catch.asp
字号:
}
</script>
</head>
<body>
<input type="button" value="View message" onclick="message()" />
</body>
</html></pre>
</td>
</tr>
</table>
<p>To take more appropriate action when an error occurs, you can add a
try...catch statement.</p>
<p>The example below contains the "Welcome guest!" example rewritten to use the
try...catch statement. Since alert() is misspelled, a JavaScript error occurs.
However, this time, the catch block catches the error and executes a custom code
to handle it. The code displays a custom error message informing the user what
happened:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table1">
<tr>
<td>
<pre><html>
<head>
<script type="text/javascript">
var txt=""
function message()
{
try
{
adddlert("Welcome guest!");
}
catch(err)
{
txt="There was an error on this page.\n\n";
txt+="Error description: " + err.description + "\n\n";
txt+="Click OK to continue.\n\n";
alert(txt);
}
}
</script>
</head>
<body>
<input type="button" value="View message" onclick="message()" />
</body>
</html></pre>
</td>
</tr>
</table>
<h3>Example 2</h3>
<p>The next example uses a confirm box to display a custom
message telling users they can click OK to continue viewing the page or click
Cancel to go to the homepage. If the confirm method returns false, the user
clicked Cancel, and the code redirects the user. If the confirm
method returns true, the code does nothing:</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table3">
<tr>
<td>
<pre><html>
<head>
<script type="text/javascript">
var txt=""
function message()
{
try
{
adddlert("Welcome guest!");
}
catch(err)
{
txt="There was an error on this page.\n\n";
txt+="Click OK to continue viewing this page,\n";
txt+="or Cancel to return to the home page.\n\n";
if(!confirm(txt))
{
document.location.href="http://www.w3schools.com/";
}
}
}
</script>
</head></pre>
<pre><body>
<input type="button" value="View message" onclick="message()" />
</body></pre>
<pre></html></pre>
</td>
</tr>
</table>
<br />
<hr />
<h2>The onerror Event</h2>
<p>The onerror event will be explained soon, but first you will learn how to use the
throw statement to create an exception. The throw
statement can be used together with the try...catch statement.</p>
<hr />
<a href="js_events.asp"><img alt="previous" border="0" src="../images/btn_previous.gif" width="100" height="20" /></a>
<a href="js_throw.asp"><img alt="next" border="0" 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>Learn XML with <oXygen/> XML Editor - Free Trial!</h2>
<table cellpadding="0"><tr>
<td valign="top"><a target="_blank" href="../../www.oxygenxml.com/default.htm">
<img src="../images/oxygenxml.png" border="0" alt="oXygen - Probably The World's Best XML Editor" /></a></td>
<td> </td>
<td valign="top">
<p><a href="../../www.oxygenxml.com/default.htm" target="_blank">oXygen</a> helps you learn to define,
edit, validate and transform XML documents. Supported technologies include XML Schema,
DTD, Relax NG, XSLT, XPath, XQuery, CSS.</p>
<p>Understand in no time how XSLT and XQuery work by using the intuitive oXygen debugger!</p>
<p>Do you have any XML related questions? Get free answers from the oXygen
<a href="../../www.oxygenxml.com/forum/default.htm" target="_blank">XML forum</a>
and from the <a href="../../www.oxygenxml.com/documentation.html" target="_blank">video</a>
demonstrations.</p>
<p><b><a href="../../www.oxygenxml.com/download.html" target="_blank">
Download a FREE 30-day trial today!</a></b></p>
</td></tr></table>
<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_try_catch.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 + -