fix(*): use fetch polyfill in IE and Edge

src/SASjs.ts

@@ -1,6 +1,10 @@
-import "isomorphic-fetch";
 import * as e6p from "es6-promise";
 (e6p as any).polyfill();
+if (isIEorEDGE()) {
+  window.fetch = undefined as any; // ensure the polyfill runs
+}
+// tslint:disable-next-line
+require("isomorphic-fetch");
 import {
   convertToCSV,
   compareTimestamps,
@@ -27,6 +31,7 @@ import {
 import { SASViyaApiClient } from "./SASViyaApiClient";
 import { SAS9ApiClient } from "./SAS9ApiClient";
 import { FileUploader } from "./FileUploader";
+import { isIEorEDGE } from "./utils/isIeOrEdge";
 
 const defaultConfig: SASjsConfig = {
   serverUrl: "",
@@ -654,9 +659,11 @@ export default class SASjs {
                 try {
                   responseJson = JSON.parse(response!.result);
                 } catch {
-                  responseJson = JSON.parse(parseWeboutResponse(response!.result));
+                  responseJson = JSON.parse(
+                    parseWeboutResponse(response!.result)
+                  );
                 }
-                
+
                 return responseJson;
               })
               .catch(async (e) => {

src/utils/isIeOrEdge.ts

@@ -0,0 +1,23 @@
+export function isIEorEDGE() {
+  const ua = window.navigator.userAgent;
+
+  const msie = ua.indexOf("MSIE ");
+  if (msie > 0) {
+    // IE 10 or older => return version number
+    return true;
+  }
+
+  const trident = ua.indexOf("Trident/");
+  if (trident > 0) {
+    return true;
+  }
+
+  const edge = ua.indexOf("Edge/");
+  if (edge > 0) {
+    // Edge (IE 12+) => return version number
+    return true;
+  }
+
+  // other browser
+  return false;
+}