使用javascript检查用户名/电子邮件是否已经存在

Question

i have a simple question.

how can i check if the username or email they entered is already exist..

i have this code,

        if(document.RegForm.user.value =="")
        {
        alert("User Name Please?");
        valid=false;
        }

that's my code for username, i don't know what code i will add to check if user name is already exist.. :-(

hmm.. also this is for the email:

        var emailExp= /^\w+[\+\.\w-]*@([\w-]+\.)*\w+[\w-]*\.([a-z]{2,4}|\d+)$/i
        strEmail=document.RegForm.eadd.value;

    if(strEmail.search(emailExp)==-1)
        {
        alert("A Valid Email Address Required");
        valid=false;
        }

what code will i add? to check if email is already exist. help me please .. :-( thank you so much guys..

Answer 1

将该表单发回时，可以在页面下面的PHP脚本中执行此检查，或者如果不需要重新加载页面就可以进行AJAX检查-尽管即使使用后一种方法，您也必须执行检查后端，或冒一些恶意用户绕过JavaScript并输入重复条目的风险。

Answer 2

You will need ajax to check if a username has been taken.

Ajax is sending and receiving data without refreshing the page.

here is a simple tutorial: http://www.w3schools.com/Ajax/ajax_example.asp

I suggest you use a javascript library like jQuery to make everything easier.

Answer 3

如果您熟悉jQuery，请查看支持远程处理的验证插件 ：）