var xmlHttp;
function createXmlHttpRequest() {
    if (window.ActiveXObject) {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();
    }
    if (!xmlHttp) {
        window.alert("你的浏览器不支持XmlHttpRequest");
    }
    return xmlHttp;
}

function $(id) {
    return document.getElementById(id);
}

function getCookie(objName) {//获取指定名称的cookie的值
    var arrStr = document.cookie.split("; ");
    for (var i = 0; i < arrStr.length; i++) {
        var temp = arrStr[i].split("=");
        if (temp[0] == objName) return unescape(temp[1]);
    }
}