利用Js函数阻止服务器控件的回发

OnClientClick="return validUserNameAndPwd()"

function validUserNameAndPwd(){
    var uName=document.getElementById("txtName");
    var uPwd=document.getElementById("txtPwd");
    var nameCount=uName.value.indexOf("*");
    var pwdCount=uPwd.value.indexOf("=");
    if (uName.value==""){
        document.getElementById("lblMessage").innerText="用户名不能为空！";
        return false;
    }
    if (uPwd.value==""){
        document.getElementById("lblMessage").innerText="密码不能为空！";
        return false;
    }
    if (nameCount>=0){
        document.getElementById("lblMessage").innerText="用户名中不能包含*号！";
        return false;
    }
    if (pwdCount>=0){
        document.getElementById("lblMessage").innerText="密码中不能包含=号！";
        return false;
    }
}