Setting of document for tracker analysis (#1613)

* Setting of document for tracker analysis

* Add comments to explain global exposing code

Author: jonathanKingston

injected/src/trackers.js

@@ -1,9 +1,14 @@
+import { getGlobal } from './utils.js';
+
 /**
  * Check if the current document origin is on the tracker list, using the provided lookup trie.
  * @param {object} trackerLookup Trie lookup of tracker domains
  * @returns {boolean} True iff the origin is a tracker.
+ *
+ * Note: getGlobal() is used in testing to get the global object,
+ * it's a work around for ESM modules are essentially singletons preventing overriding of global variables.
  */
-export function isTrackerOrigin(trackerLookup, originHostname = document.location.hostname) {
+export function isTrackerOrigin(trackerLookup, originHostname = getGlobal().document.location.hostname) {
     const parts = originHostname.split('.').reverse();
     let node = trackerLookup;
     for (const sub of parts) {

injected/src/utils.js

@@ -49,6 +49,14 @@ export function setGlobal(globalObjIn) {
     Error = globalObj.Error;
 }
 
+/**
+ * Used for testing to allow other files to override the globals used within this file.
+ * @returns {globalThis} the global object
+ */
+export function getGlobal() {
+    return globalObj;
+}
+
 // linear feedback shift register to find a random approximation
 export function nextRandom(v) {
     return Math.abs((v >> 1) | (((v << 62) ^ (v << 61)) & (~(~0 << 63) << 62)));