Why is ajax request working cross-domain in the google extension sample without jsonp? -

i going through tutorial making simple chrome extension gets images flicker api , loads them extension popup.making simple chrome extension

i cant understand 1 thing. ajax request made here simple request. why working cross-domain. not jsonp. script file popup.js follows

    // copyright (c) 2012 chromium authors. rights reserved. // use of source code governed bsd-style license can // found in license file.  /**  * global variable containing query we'd pass flickr. in  * case, kittens!  *  * @type {string}  */ var query = 'kittens';  var kittengenerator = {   /**    * flickr url give lots , lots of whatever we're looking for.    *    * see http://www.flickr.com/services/api/flickr.photos.search.html    * details construction of url.    *    * @type {string}    * @private    */   searchonflickr_: 'https://secure.flickr.com/services/rest/?' +       'method=flickr.photos.search&' +       'api_key=90485e931f687a9b9c2a66bf58a3861a&' +       'text=' + encodeuricomponent(query) + '&' +       'safe_search=1&' +       'content_type=1&' +       'sort=interestingness-desc&' +       'per_page=20',    /**    * sends xhr request grab photos of lots , lots of kittens.    * xhr's 'onload' event hooks 'showphotos_' method.    *    * @public    */   requestkittens: function() {     var req = new xmlhttprequest();     req.open("get", this.searchonflickr_, true);     req.onload = this.showphotos_.bind(this);     req.send(null);   },    /**    * handle 'onload' event of our kitten xhr request, generated in    * 'requestkittens', generating 'img' elements, , stuffing them    * document display.    *    * @param {progressevent} e xhr progressevent.    * @private    */   showphotos_: function (e) {     var kittens = e.target.responsexml.queryselectorall('photo');     (var = 0; < kittens.length; i++) {       var img = document.createelement('img');       img.src = this.constructkittenurl_(kittens[i]);       img.setattribute('alt', kittens[i].getattribute('title'));       document.body.appendchild(img);     }   },    /**    * given photo, construct url using method outlined @    * http://www.flickr.com/services/api/misc.urlkittenl    *    * @param {domelement} kitten.    * @return {string} kitten's url.    * @private    */   constructkittenurl_: function (photo) {     return "http://farm" + photo.getattribute("farm") +         ".static.flickr.com/" + photo.getattribute("server") +         "/" + photo.getattribute("id") +         "_" + photo.getattribute("secret") +         "_s.jpg";   } };  // run our kitten generation script document's dom ready. document.addeventlistener('domcontentloaded', function () {   kittengenerator.requestkittens(); }); 

i got it. cors.

in flicker api, response header has access control allow origin header set *. hence, ajax request work.

you need edit server configuration file if u need set header. default not *.