Remove dependency on window to work in Web Workers (#660)

* Bugfix - replace window global with self

* Adjust changes to better fit linter

* Remove additional references to `window`

---------

Co-authored-by: Marius Kleidl <[email protected]>

Author: rashyad

lib/browser/index.js

@@ -28,9 +28,11 @@ class Upload extends BaseUpload {
   }
 }
 
-const { XMLHttpRequest, Blob } = window
-
-const isSupported = XMLHttpRequest && Blob && typeof Blob.prototype.slice === 'function'
+// Note: We don't reference `window` here because these classes also exist in a Web Worker's context.
+const isSupported =
+  typeof XMLHttpRequest === 'function' &&
+  typeof Blob === 'function' &&
+  typeof Blob.prototype.slice === 'function'
 
 export {
   Upload,

lib/browser/urlStorage.js

@@ -1,5 +1,6 @@
 let hasStorage = false
 try {
+  // Note: localStorage does not exist in the Web Worker's context, so we must use window here.
   hasStorage = 'localStorage' in window
 
   // Attempt to store and read entries from the local storage to detect Private

lib/upload.js

@@ -984,14 +984,10 @@ async function sendRequest(req, body, options) {
  */
 function isOnline() {
   let online = true
-  if (
-    typeof window !== 'undefined' &&
-    // eslint-disable-next-line no-undef
-    'navigator' in window &&
-    // eslint-disable-next-line no-undef
-    window.navigator.onLine === false
-  ) {
-    // eslint-disable-line no-undef
+  // Note: We don't reference `window` here because the navigator object also exists
+  // in a Web Worker's context.
+  // eslint-disable-next-line no-undef
+  if (typeof navigator !== 'undefined' && navigator.onLine === false) {
     online = false
   }