XMLHttprequest发送一个空帖子

I'm using the following code to send a request:

var ajaxHandler = new XMLHttpRequest();

ajaxHandler.onreadystatechange = function()
{
   if(ajaxHandler.readyState == 4)
   {
      console.log(ajaxHandler.responseText);
   }
}

ajaxHandler.open("POST", "filterCards", true);
ajaxHandler.send("category="+category+"&tag="+tag);

On the PHP side, I have this:

var_dump($_POST);

However, even though both the variables of category and tag have values, the console logs an empty array. What am I doing wrong with the post?

Add setRequestHeader before your send call:

ajaxHandler.setRequestHeader("Content-type","application/x-www-form-urlencoded");
ajaxHandler.send("category="+category+"&tag="+tag);

Replace:

   if(ajaxHandler.readyState == 4)
   {
      console.log(ajaxHandler.responseText);
   }

with

   if(ajaxHandler.readyState == 4 && ajaxHandler.status==200)
   {
      console.log(ajaxHandler.responseText);
   }

Hope this helps.