jQuery - get AJAX response headers

Question

How do we get access to the response headers when we fire an ajax request using jQuery? I tried with the below code as per the suggestions given in some sites. But xhr object is coming as null. I see an xhr object in this context. But it doesn't have methods to access response headers.

function SampleMethod() {
  var savedThis = this;
  this.invokeProcedure = function(procedurePath) {
    $.ajax({
      type: "GET",
      url: procedurePath,
      dataType: "json",
      success: function(data,status,xhr) savedThis.resultSetHandler(data,status,xhr);}
    });
  }

  this.resultSetHandler=function(data,status,xhrObj){
    //Handle the result
  }

  this.errorHandler = function(args) {
    //Handle the result
  }

}

var sampleObj = new SampleMethod();
sampleObj.invokeProcedure('url');

Answer 1

For backward compatibility with XMLHttpRequest, a jqXHR object will expose the following properties and methods: getAllResponseHeaders() and getResponseHeader(). From the $.ajax() doc : http://api.jquery.com/jQuery.ajax/

For jQuery > 1.3

success: function(res, status, xhr) { 
  alert(xhr.getResponseHeader("myHeader"));
}