📄 xml_http.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>The XMLHttpRequest Object</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=xmlmaster" 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>XML Basic</b><br />
<a class="left" target="_top" href="default.asp" >XML HOME</a><br />
<a class="left" target="_top" href="xml_whatis.asp" >XML Introduction</a><br />
<a class="left" target="_top" href="xml_usedfor.asp" >XML How to use</a><br />
<a class="left" target="_top" href="xml_tree.asp" >XML Tree</a><br />
<a class="left" target="_top" href="xml_syntax.asp" >XML Syntax</a><br />
<a class="left" target="_top" href="xml_elements.asp" >XML Elements</a><br />
<a class="left" target="_top" href="xml_attributes.asp" >XML Attributes</a><br />
<a class="left" target="_top" href="xml_dtd.asp" >XML Validation</a><br />
<a class="left" target="_top" href="xml_validator.asp" >XML Validator</a><br />
<a class="left" target="_top" href="xml_view.asp" >XML Viewing</a><br />
<a class="left" target="_top" href="xml_display.asp" >XML CSS</a><br />
<a class="left" target="_top" href="xml_xsl.asp" >XML XSLT</a><br />
<br />
<b>XML JavaScript</b><br />
<a class="left" target="_top" href="xml_parser.asp" >XML Parser</a><br />
<a class="left" target="_top" href="xml_dom.asp" >XML DOM</a><br />
<a class="left" target="_top" href="xml_to_html.asp" >XML to HTML</a><br />
<a class="left" target="_top" href="xml_http.asp" style='font-weight:bold;'>XML HTTP Request</a><br />
<a class="left" target="_top" href="xml_applications.asp" >XML Application</a><br />
<br />
<b>XML Advanced</b><br />
<a class="left" target="_top" href="xml_namespaces.asp" >XML Namespaces</a><br />
<a class="left" target="_top" href="xml_cdata.asp" >XML CDATA</a><br />
<a class="left" target="_top" href="xml_encoding.asp" >XML Encoding</a><br />
<a class="left" target="_top" href="xml_server.asp" >XML Server</a><br />
<a class="left" target="_top" href="xml_dom_advanced.asp" >XML DOM Advanced</a><br />
<a class="left" target="_top" href="xml_dont.asp" >XML Don't</a><br />
<a class="left" target="_top" href="xml_technologies.asp" >XML Technologies</a><br />
<a class="left" target="_top" href="xml_real_life.asp" >XML in Real Life</a><br />
<a class="left" target="_top" href="xml_editors.asp" >XML Editors</a><br />
<a class="left" target="_top" href="xml_summary.asp" >XML Summary</a><br />
<br />
<b>Examples/Quiz</b><br />
<a class="left" target="_top" href="xml_examples.asp" >XML Examples</a><br />
<a class="left" target="_top" href="xml_quiz.asp" >XML Quiz</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>The XMLHttpRequest Object</h1>
<a href="xml_to_html.asp"><img alt="previous" border="0" src="../images/btn_previous.gif" width="100" height="20" /></a>
<a href="xml_applications.asp"><img alt="next" border="0" src="../images/btn_next.gif" width="100" height="20" /></a>
<hr />
<p class="intro">The XMLHttpRequest object provides a way to communicate with a
server after a web page has loaded.</p>
<hr />
<h2>What is the XMLHttpRequest Object?</h2>
<p>The XMLHttpRequest object is <b>the developers dream</b>, because you can:</p>
<ul>
<li>Update a web page with new data without reloading the page</li>
<li>Request data from a server after the page has loaded </li>
<li>Receive data from a server after the page has loaded</li>
<li>Send data to a server in the background</li>
</ul>
<p>The XMLHttpRequest object is supported in all modern browsers.</p>
<p>Example: <a target="_blank" href="tryit.asp@filename=tryxml_httpsuggest">XML
HTTP communication with a server while typing input</a></p>
<hr />
<h2>Creating an XMLHttpRequest Object</h2>
<p>Creating an XMLHttpRequest object is done with one single line of JavaScript.</p>
<p>In all modern browsers (including IE7):</p>
<table border="1" width="100%" class="ex" cellspacing="0" id="table1">
<tr>
<td>
<pre>var xmlhttp=new XMLHttpRequest()</pre>
</td>
</tr>
</table>
<p>In Internet Explorer 5 and 6:</p>
<table border="1" width="100%" class="ex" cellspacing="0" id="table2">
<tr>
<td>
<pre>var xmlhttp=new ActiveXObject("Microsoft.XMLHTTP")</pre>
</td>
</tr>
</table>
<h3>Example</h3>
<table border="1" width="100%" class="ex" cellspacing="0" id="table7">
<tr>
<td>
<pre><script type="text/javascript">
var xmlhttp;
function loadXMLDoc(url)
{
xmlhttp=null;
if (window.XMLHttpRequest)
{// code for all new browsers
xmlhttp=new XMLHttpRequest();
}
else if (window.ActiveXObject)
{// code for IE5 and IE6
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
if (xmlhttp!=null)
{
xmlhttp.onreadystatechange=state_Change;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}
else
{
alert("Your browser does not support XMLHTTP.");
}
}</pre>
<pre>function state_Change()
{
if (xmlhttp.readyState==4)
{// 4 = "loaded"
if (xmlhttp.status==200)
{// 200 = OK
// ...our code here...
}
else
{
alert("Problem retrieving XML data");
}
}
}
</script></pre>
</td>
</tr>
</table>
<p><a target="_blank" href="tryit.asp@filename=tryxml_httprequest_js">Try it yourself using JavaScript</a></p>
<p><b>Note:</b> onreadystatechange is an event handler. The value (state_Change)
is the name of a function which is
triggered when the state of the XMLHttpRequest object changes. States run from 0 (uninitialized)
to 4 (complete). Only when the state = 4, we can execute our code.</p>
⌨️ 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 + -