需要在浏览器关闭（浏览器程序关闭及浏览器标签关闭）时，使用异步方法向服务器端回发一些信息。
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>HTMLPage3</title> <script language="javascript" type="text/javascript"> var xmlHttp; function createHttpRequest() { if (!window.XMLHttpRequest) { window.XMLHttpRequest = function() { var progIDs = [ 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP.2.6', 'Msxml2.XMLHTTP', 'Microsoft.XMLHTTP', 'MSXML.XMLHTTP' ]; for (var i = 0; i < progIDs.length; i++) { try { xmlHttp = new ActiveXObject(progIDs[i]); break; } catch (ex) { } } } } else { xmlHttp = new XMLHttpRequest(); } } function doSearch() { createHttpRequest(); var url = "myPage.aspx?id=" if(document.getElementById("txt") != null) { url = url + escape(document.getElementById("txt").value) } else { url = url + "-1"; } if(xmlHttp != null) { xmlHttp.open("GET", url, true); xmlHttp.send(null); //alert("Send Complete!"); } } window.onbeforeunload = function() { doSearch(); } </script> </head> <body> <h1>HTMLPage3</h1><br /> <input type="text" id="txt" /> <input type="button" id="btn" value="Click" onclick="doSearch();" /> </body> </html>