undefined 不是函数：document.create 元素

Question

我收到系统用户名的错误“未捕获的类型错误：未定义不是函数”。我已经在这里工作了 2 个多小时了，我不明白这是怎么定义的？

function systemUsername()
{
/*consists of the first
alphabetic characters found in the Family name, street address, Given name; the numerical day of the
month; and the numerical seconds field of the time of submission. E.g.: A user registers with name
Bernardo O’Higgins, address 213 Liberator St, at 12:31:16 on 25 April 2014. His system username is
OLB2516*/

var systemUsername = document.createElement("systemUsername");
var lastname = document.forms["userinfo"]["famName"].value;
var Address = document.forms["userinfo"]["address"].value;
//var withNoDigits = address.replace(/[0-9]/g, '');
var firstname = document.forms["userinfo"]["firstName"].value;
var dateStamp = new Date();
var dayNum = dateStamp.getDate();
var Seconds = dateStamp.getSeconds();

if (dayNum<10)
{
    var x = '0';
    dayNum = x + dayNum;
}
    alert(dayNum);

if (Seconds<10)
{
    var x = '0';
    Seconds = x + Seconds;
}
    alert(Seconds);

var tempSU = lastname.charAt(0)+Address.charAt(0)+firstname.charAt(0)+dayNum.charAt(0)+dayNum.charAt(1)+Seconds.charAt(0)+Seconds.charAt(1);
systemUsername.setAttribute("type", "hidden");
systemUsername.setAttribute("name", "systemName");
systemUsername.setAttribute("value", "tempSU");
document.getElementById("userinfo").appendChild(systemUsername);
alert("tempSU: ".tempSU);

}

Answer 1

试试这个，使用+代替.进行连接

alert("tempSU: " + tempSU);

而不是

 alert("tempSU: ".tempSU);

演示：http://jsfiddle.net/5yXAL/