var username = document.getElementById("username");
            var password = document.getElementById("password");
            var repassword = document.getElementById("password-2");
            var usernameReg = /^[0-9a-zA-Z]{3,10}$/;
            var passwordReg = /^\w{6,20}$/;
            if(!usernameReg.test(username.value)){
                alert("用户名必须是3-10位英文字母或数字");
                return false;
            }
            if(!passwordReg.test(password.value)){
                alert("口令必须是6-20位");
                return false;
            }
            if(password.value !== repassword.value){
                alert("两次输入口令必须一致");
                return false;
            }
            return true;