demo/dist/demo.js
function fetch(url) {
	  var responseType = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 'text';
	  return new Promise(function (resolve, reject) {
	    try {
	      var request = new XMLHttpRequest(); // Check for CORS support

	      if (!('withCredentials' in request)) {
	        return;
	      }

	      request.addEventListener('load', function () {
	        if (responseType === 'text') {
	          try {
	            resolve(JSON.parse(request.responseText));
	          } catch (e) {
	            resolve(request.responseText);
	          }
	        } else {
	          resolve(request.response);
	        }
	      });
	      request.addEventListener('error', function () {
	        throw new Error(request.status);
	      });
	      request.open('GET', url, true); // Set the required response type

	      request.responseType = responseType;
	      request.send();
	    } catch (e) {
	      reject(e);
	    }
	  });
	}
function fetch(url) {
	  var responseType = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 'text';
	  return new Promise(function (resolve, reject) {
	    try {
	      var request = new XMLHttpRequest(); // Check for CORS support

	      if (!('withCredentials' in request)) {
	        return;
	      }

	      request.addEventListener('load', function () {
	        if (responseType === 'text') {
	          try {
	            resolve(JSON.parse(request.responseText));
	          } catch (e) {
	            resolve(request.responseText);
	          }
	        } else {
	          resolve(request.response);
	        }
	      });
	      request.addEventListener('error', function () {
	        throw new Error(request.status);
	      });
	      request.open('GET', url, true); // Set the required response type

	      request.responseType = responseType;
	      request.send();
	    } catch (e) {
	      reject(e);
	    }
	  });
	}
========================================================================== Fetch wrapper Using XHR to avoid issues with older browsers ==========================================================================