diff --git a/web/download_manager.js b/web/download_manager.js
index 3ac266d66..e7d031c63 100644
--- a/web/download_manager.js
+++ b/web/download_manager.js
@@ -47,9 +47,7 @@ function download(blobUrl, filename) {
  * @implements {IDownloadManager}
  */
 class DownloadManager {
-  constructor() {
-    this._openBlobUrls = new WeakMap();
-  }
+  #openBlobUrls = new WeakMap();
 
   downloadUrl(url, filename) {
     if (!createValidAbsoluteUrl(url, "http://example.com")) {
@@ -74,10 +72,10 @@ class DownloadManager {
     const contentType = isPdfData ? "application/pdf" : "";
 
     if (isPdfData) {
-      let blobUrl = this._openBlobUrls.get(element);
+      let blobUrl = this.#openBlobUrls.get(element);
       if (!blobUrl) {
         blobUrl = URL.createObjectURL(new Blob([data], { type: contentType }));
-        this._openBlobUrls.set(element, blobUrl);
+        this.#openBlobUrls.set(element, blobUrl);
       }
       let viewerUrl;
       if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
@@ -101,7 +99,7 @@ class DownloadManager {
         // Release the `blobUrl`, since opening it failed, and fallback to
         // downloading the PDF file.
         URL.revokeObjectURL(blobUrl);
-        this._openBlobUrls.delete(element);
+        this.#openBlobUrls.delete(element);
       }
     }
 
diff --git a/web/event_utils.js b/web/event_utils.js
index 077699598..3ae6910be 100644
--- a/web/event_utils.js
+++ b/web/event_utils.js
@@ -75,9 +75,7 @@ function waitOnEventOrTimeout({ target, name, delay = 0 }) {
  * and `off` methods. To raise an event, the `dispatch` method shall be used.
  */
 class EventBus {
-  constructor() {
-    this._listeners = Object.create(null);
-  }
+  #listeners = Object.create(null);
 
   /**
    * @param {string} eventName
@@ -108,7 +106,7 @@ class EventBus {
    * @param {Object} data
    */
   dispatch(eventName, data) {
-    const eventListeners = this._listeners[eventName];
+    const eventListeners = this.#listeners[eventName];
     if (!eventListeners || eventListeners.length === 0) {
       return;
     }
@@ -139,7 +137,7 @@ class EventBus {
    * @ignore
    */
   _on(eventName, listener, options = null) {
-    const eventListeners = (this._listeners[eventName] ||= []);
+    const eventListeners = (this.#listeners[eventName] ||= []);
     eventListeners.push({
       listener,
       external: options?.external === true,
@@ -151,7 +149,7 @@ class EventBus {
    * @ignore
    */
   _off(eventName, listener, options = null) {
-    const eventListeners = this._listeners[eventName];
+    const eventListeners = this.#listeners[eventName];
     if (!eventListeners) {
       return;
     }
diff --git a/web/firefoxcom.js b/web/firefoxcom.js
index 0e5172b53..a157b282e 100644
--- a/web/firefoxcom.js
+++ b/web/firefoxcom.js
@@ -100,9 +100,7 @@ class FirefoxCom {
 }
 
 class DownloadManager {
-  constructor() {
-    this._openBlobUrls = new WeakMap();
-  }
+  #openBlobUrls = new WeakMap();
 
   downloadUrl(url, filename) {
     FirefoxCom.request("download", {
@@ -132,10 +130,10 @@ class DownloadManager {
     const contentType = isPdfData ? "application/pdf" : "";
 
     if (isPdfData) {
-      let blobUrl = this._openBlobUrls.get(element);
+      let blobUrl = this.#openBlobUrls.get(element);
       if (!blobUrl) {
         blobUrl = URL.createObjectURL(new Blob([data], { type: contentType }));
-        this._openBlobUrls.set(element, blobUrl);
+        this.#openBlobUrls.set(element, blobUrl);
       }
       // Let Firefox's content handler catch the URL and display the PDF.
       const viewerUrl = blobUrl + "#filename=" + encodeURIComponent(filename);
@@ -148,7 +146,7 @@ class DownloadManager {
         // Release the `blobUrl`, since opening it failed, and fallback to
         // downloading the PDF file.
         URL.revokeObjectURL(blobUrl);
-        this._openBlobUrls.delete(element);
+        this.#openBlobUrls.delete(element);
       }
     }