为什么在ajax或javascript函数调用之后输入字段被禁用？

Question

I am making a simple signup form where I check whether the email users enters already exists or not. This is done via onChange function which in turn checks through ajax whether the email entered by the user is available or not. Currently I just show an alert box if the email is already registered. But I have noticed a strange behavior. After clicking the ok button in alert box the whole form gets disabled for text input. I cant enter the text into remaining fields and refreshing the page is the only solution to make the form active for input again. Why this is so? And how do I prevent it?

here is my code:

One of my input field

<input type="email" name="email" onChange="checkEmail()" id="email"/>

And here is the javascript and ajax code for checking email if it exists or not:

       function checkEmail()
         {

            var email=$('#email').val();


            var dataString = 'email=' + email;              
            $.ajax({
                type: "POST",
                url: "<?=base_url();?>home/check_email",            
                data: dataString,                           
                dataType:"html",
                success: function(msg)
                    {
                        if(msg=="1")
                        {
                            alert("The email already exists in our records!");
                        }

                    }
            });
        }

Answer 1

您必须使用onBlur

<input type="email" name="email" onBlur="checkEmail()" id="email"/>

Answer 2

You should use onBlur, this event triggered when you leave the textbox. Otherwise it would be called every time a character in the textbox changes.

<input type="email" name="email" onBlur="checkEmail()" id="email"/>

Answer 3

或者如果您确实想检查每个按键（无论出于何种原因），请使用按键事件

 <input type="email" name="email" onKeyPress="checkEmail()" id="email"/>