javascript - How to get response headers from iron-form Polymer -

i have form, submit so:

form.addeventlistener("iron-form-response", function(event) {        //how can access response headers here?                       });        form.submit(); 

i know way can access response body:

event.detail.response 

but want server response headers. need it, because response may contain in headers tokens, must store in cookies.

the event.detail <iron-request>, exposes underlying xmlhttprequest via e.detail.xhr, allows use getresponseheader(name) specific header:

_onresponse(e) {   const header = e.detail.xhr.getresponseheader('x-special-header');   ... } 

example:

<dom-module id="x-foo">   <template>     <iron-form on-iron-form-response="_onresponse">       <form method="post"             action="//httpbin.org/post">         <label for="myname">my name</label>         <input type="text" id="myname" name="name">         <button>submit</button>       </form>     </iron-form>   </template>    <script>   class xfoo extends polymer.element {     static is() { return 'x-foo'; }      _onresponse(e) {       console.debug('response header("content-type")', e.detail.xhr.getresponseheader('content-type'));       console.debug('all response headers', e.detail.xhr.getallresponseheaders())     }   }   customelements.define(xfoo.is, xfoo);   </script> </dom-module> 

demo