function getXmlHttpPrefix() {
if (getXmlHttpPrefix.prefix)
return getXmlHttpPrefix.prefix;
var prefixes = ["MSXML2", "Microsoft", "MSXML", "MSXML3"];
var o;
for (var i = 0; i < prefixes.length; i++) {
try {
// try to create the objects
o = new ActiveXObject(prefixes[i] + ".XmlHttp");
return getXmlHttpPrefix.prefix = prefixes[i];
}
catch (ex) {};
}
throw new Error("Could not find an installed XML parser");
}
//////////////////////////
// Start the Real stuff //
//////////////////////////
// XmlHttp factory
function XmlHttp() {}
XmlHttp.create = function () {
try {
if (window.XMLHttpRequest) {
var req = new XMLHttpRequest();
// some versions of Moz do not support the readyState property
// and the onreadystate event so we patch it!
if (req.readyState == null) {
req.readyState = 1;
req.addEventListener("load", function () {
req.readyState = 4;
if (typeof req.onreadystatechange == "function")
req.onreadystatechange();
}, false);
}
return req;
}
if (window.ActiveXObject) {
return new ActiveXObject(getXmlHttpPrefix() + ".XmlHttp");
}
}
catch (ex) {}
// fell through
throw new Error("Your browser does not support XmlHttp objects");
};
-------------------------------
var xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
var xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
var xmlHttp=new ActiveXObject("MSXML.XMLHTTP");
var xmlHttp=new ActiveXObject("MSXML3.XMLHTTP");
这几个代码都有可能, 上面的代码就遍历这些对象选择一个创建成功的出来, 区别就是操作系统带的 MSXML 包的版本不一样, 这些包是 ActiveX 控件, IE 和很多 Windows 应用都可能用到它. 对于 Mozilla, Firefox, 直接用
var xmlHttp = new XMLHttpRequest();
就可以了.
