在Ajax / jQuery中实现“成功”(Function 'success' in Ajax/jQuery)

 我在使用Ajax调用的成功函数显示值时遇到问题。 我的代码如下。 
 
$.ajax({
    type: "POST",
    url: "http://localhost/practical 8/checkuser.php",
    data: form_data,
    success: function(response)
    {
        if(response == 'success'){
            $("#errorUsername").html("<label class='error'>"+response+"</label>");
        }else if(response == 'fail'){
            $("#errorUsername").html("<label class='error'>"+response+"</label>");
        }
    }
});
 
 我的checkuser.php基本上回声“成功”或“失败”。 
 
 我的成功函数中的if和else if语句不起作用。 但是做 
 
$.ajax({
    type: "POST",
    url: "http://localhost/practical 8/checkuser.php",
    data: form_data,
    success: function(response)
    {
            $("#errorUsername").html("<label class='error'>"+response+"</label>");
        }
    }
});
 
 工作得很好。 我究竟做错了什么？ 

I'm having problems displaying a value from the success function of my Ajax call. My code is as follows.
 
$.ajax({
    type: "POST",
    url: "http://localhost/practical 8/checkuser.php",
    data: form_data,
    success: function(response)
    {
        if(response == 'success'){
            $("#errorUsername").html("<label class='error'>"+response+"</label>");
        }else if(response == 'fail'){
            $("#errorUsername").html("<label class='error'>"+response+"</label>");
        }
    }
});
 
My checkuser.php basically echos "succcess" or "fail".
 
My if and else if statements in my success function are not working. But doing
 
$.ajax({
    type: "POST",
    url: "http://localhost/practical 8/checkuser.php",
    data: form_data,
    success: function(response)
    {
            $("#errorUsername").html("<label class='error'>"+response+"</label>");
        }
    }
});
 
works perfectly. What am I doing wrong?

原文：https://stackoverflow.com/questions/6020401