var username = document.getElementById("username").value;
    var password = document.getElementById("password").value;
    var re_password = document.getElementById("password-2").value;
    var nametest = /\w{3,10}/;
    var passtest = /.{6,20}/;
    if (!nametest.test(username)){
        alert("用户名必须是3-10位英文字母或数字");
        return false;
    };
    if (!passtest.test(password)){
        alert("口令必须是6-20位");
        return false;
    };
    if (password !== re_password){
        alert("两次输入口令必须一致");
        return false;
    };
    return true;