CheckSPWebResource

(function($) {
"use strict";

function checkSPWebResource(url, async) {
  var
    endpoint = url.match(/^http[s]?:\/\//i) || url.match("^"+_spPageContextInfo.webServerRelativeUrl)
            ? url
            :  _spPageContextInfo.webServerRelativeUrl.replace(/\/$/g,'')
                + '/' + url.replace(/^\//g,''),
    p = $.Deferred();

  $.ajax({ type: 'HEAD', url: endpoint, async: (typeof async !== "undefined" ? async : true) })
    .done(function(response, textStatus, xhr) { 
      p.resolve({ status: true, url: endpoint });
    })
    .fail(function(xhr, textStatus, err) {
      p.reject({ status: false, url: endpoint });
    });
  return p.promise();
}

})(jQuery);