function ajaxFunction() {
    try {
        // Firefox, Opera 8.0+, Safari
        xmlHttp = new XMLHttpRequest();
    }
    catch(e) {
        // Internet Explorer
        try {
            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch(e) {
            try {
                xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            catch(e) {
                alert("ÄúµÄä¯ÀÀÆ÷²»Ö§³ÖAJAX£¡");
				xmlHttp = false;
            }
        }
    }
	return xmlHttp;
}