jquery how to check response type for ajax call

How can I determine the response type of ajax call in Jquery? At times, the server sends json response and at times it sends only the html for display purposes. Right now I am using

if(response.indexOf('Error'))
  //popup error message
else
 response.username
 response.address

You can try it like:

$.ajax({
  type: "POST",
  url: "your url goes here", 
  data: "data to be sent", 
  success: function(response, status, xhr){ 
    var ct = xhr.getResponseHeader("content-type") || "";
    if (ct.indexOf('html') > -1) {
      //do something
    }
    if (ct.indexOf('json') > -1) {
      // handle json here
    } 
  }
});

Basically it is also using indexOf but it seems more reliable.

You can simply use javascript's easy method to check the type

i.e.

if(typeof response=="object")
{
 // Response is javascript object
}
else
{
 // Response is HTML
}

If you use this method you don't have to write 2 extra parameter in the success callback.