PHP、MySQL、jQuery、AJAX: json数据返回正确的响应，但前端返回错误。

I have a user registration form. I am doing server side validation on the fly via AJAX. The quick summary of my problem is that upon validating 2 fields, I get error for the second field validation. If I comment first field, then the 2nd field does not show any error. It has this weird behavior. More details below:I have a user registration form. I am doing ser