js中判断用户输入的值是否为空的简单实例_javascript技巧

这是摘自的我一个项目的中的用户注册页面.对于大多数人来说,这都几乎是100%经历过的.
贴代码吧,这些代码都是用js写的. 不难,很容易看懂. 看的时候,只要区别两个js类就行了.
前台页面代码:reguser.aspx
代码如下:
<%@ Page language="c#" Codebehind="RegUser.aspx.cs" AutoEventWireup="false" Inherits="Enterprise.Web.RegUser" %>











var reg = {};
reg.userName = '';
reg.password = '';
reg.confirmPassword = '';
reg.question = '';
reg.answer = '';
reg.url = '';
reg.sex = 1;
reg.email = '';
reg.tel = '';
reg.mobile = '';
reg.qq = '';
reg.address = '';
reg.postalcode = '';
reg.form = null;

function btnSubmit_onclick()
{
reg.form = document.forms[0];
var comFun = new commonFunction();

if(!comFun.checkIsEmpty(reg.form))
{
return false;
}

if(comFun.$getElementById('txtPassword').value!=comFun.$getElementById('txtConfirmPassword').value)
{
alert('两次密码输入不一致');
comFun.$getElementById('txtConfirmPassword').select();
return false;
}

reg.userName = comFun.$getElementById('txtUserName');
reg.password = comFun.$getElementById('txtPassword');
reg.question = comFun.$getElementById('txtQuestion');
reg.answer = comFun.$getElementById('txtAnswer');
reg.url = comFun.$getElementById('txtUrl');
reg.email = comFun.$getElementById('txtEmail');
reg.tel = comFun.$getElementById('txtTel');
reg.mobile = comFun.$getElementById('txtMobile');
reg.qq = comFun.$getElementById('txtQQ');
reg.address = comFun.$getElementById('txtAddress');
reg.postalcode = comFun.$getElementById('txtPostalcode');

var es = comFun.$getElementsByName('sex');
var eL = es.length;
for(var i=0; i {
var e = es[i];
if(e.checked)
{
reg.sex = e.value;
break;
}
}

RegUser.Reg(reg.userName.value, reg.password.value, reg.question.value, reg.answer.value, reg.url.value, reg.sex.value, reg.email.value, reg.tel.value, reg.mobile.value, reg.qq.value, reg.address.value, reg.postalcode.value, callback_Reg);
}

function callback_Reg(res)
{
var rv = res.value;
if(rv)
{
alert('注册成功!');
window.location.href='/Default.aspx';
}
else
{
alert('有错误发生,注册失败!有可能是用户名或者域名被别人注册过了！');
}
}

// 检测用户名的域名是否被其它用户注册过了
function checkIsRegistered(obj, errorS, t)
{
var v = obj.value;

var rv = RegUser.CheckIsRegistered(v, t).value;
if(rv)
{
alert(errorS);
obj.select();
return false;
}
}







在上面的代码中,有包含了一个CommonFunction.js文件,下面这是他的内容:
代码如下:
/***********************************************************
*
* 公共js函数
*
***********************************************************/
function commonFunction()
{
// check value is null or empty
this.checkIsEmpty = function(obj)
{
var flag = true;
for(var i=0; i {
var e = obj.item(i);
if(e.isRequired)
{
if(e.value=='')
{
alert(e.errorSForEmpty);
e.focus();
flag = false;
break;
}
}

if(e.isValidate)
{
if(this.checkValidate(e)==false)
{
alert(e.errorSForValidate);
e.select();
e.focus();
flag = false;
break;
}
}
}

return flag;
}

// check value is validate
this.checkValidate = function(e)
{
var v = e.value;
if(v!='')
{
return this.checkReg(e.validatePattern, v);
}
}

// regexp validate
this.checkReg = function(pattern, value)
{
pattern = pattern.substring(1, pattern.length-1);
var reg = new RegExp(pattern);
if(!reg.test(value))
{
return false;
}
}

// return an Element By id object for what id.
this.$getElementById = function(id)
{
var e = document.getElementById(id);

if(e!='undefined')
{
return e;
}

return;
}

// return an Element By name object for what id.
this.$getElementsByName = function(id)
{
var e = document.getElementsByName(id);

if(e!='undefined')
{
return e;
}

return;
}
}

贴一张效果图片: