diff --git a/js/App.js b/js/App.js
index e19b3e878..649571593 100644
--- a/js/App.js
+++ b/js/App.js
@@ -688,15 +688,16 @@ const App = {
    checkBrowserFeatures: function() {
       let errorMsg = "";
 
-      ['MutationObserver'].forEach(function(wf) {
-         if (!(wf in window)) {
-            errorMsg = `Browser feature check failed: <code>window.${wf}</code> not found.`;
+      ['MutationObserver', 'requestIdleCallback'].forEach((t) => {
+         if (!(t in window)) {
+            errorMsg = `Browser check failed: <code>window.${t}</code> not found.`;
             throw new Error(errorMsg);
          }
       });
 
-      if (errorMsg) {
-         this.Error.fatal(errorMsg, {info: navigator.userAgent});
+      if (typeof Promise.allSettled == "undefined") {
+         errorMsg = `Browser check failed: <code>Promise.allSettled</code> is not defined.`;
+         throw new Error(errorMsg);
       }
 
       return errorMsg == "";
diff --git a/js/Feeds.js b/js/Feeds.js
index 46d978cb4..7b6366959 100644
--- a/js/Feeds.js
+++ b/js/Feeds.js
@@ -311,12 +311,9 @@ const	Feeds = {
 	setActive: function(id, is_cat) {
 		console.log('setActive', id, is_cat);
 
-		if ('requestIdleCallback' in window)
-			window.requestIdleCallback(() => {
-				App.Hash.set({f: id, c: is_cat ? 1 : 0});
-			});
-		else
+		window.requestIdleCallback(() => {
 			App.Hash.set({f: id, c: is_cat ? 1 : 0});
+		});
 
 		this._active_feed_id = id;
 		this._active_feed_is_cat = is_cat;
diff --git a/js/Headlines.js b/js/Headlines.js
index 028f277ff..08192ea6b 100755
--- a/js/Headlines.js
+++ b/js/Headlines.js
@@ -76,12 +76,9 @@ const Headlines = {
 
 		Headlines.updateSelectedPrompt();
 
-		if ('requestIdleCallback' in window)
-			window.requestIdleCallback(() => {
-				Headlines.syncModified(modified);
-			});
-		else
+		window.requestIdleCallback(() => {
 			Headlines.syncModified(modified);
+		});
 	}),
 	syncModified: function (modified) {
 		const ops = {
@@ -175,7 +172,7 @@ const Headlines = {
 			});
 		}
 
-		Promise.all(promises).then((results) => {
+		Promise.allSettled(promises).then((results) => {
 			let feeds = [];
 			let labels = [];
 
diff --git a/js/PrefHelpers.js b/js/PrefHelpers.js
index 3f738aa95..8a5c5857e 100644
--- a/js/PrefHelpers.js
+++ b/js/PrefHelpers.js
@@ -510,12 +510,10 @@ const	Helpers = {
 				search: function() {
 					this.search_query = this.attr('value').search.toLowerCase();
 
-					if ('requestIdleCallback' in window)
-						window.requestIdleCallback(() => {
-							this.render_contents();
-						});
-					else
+					window.requestIdleCallback(() => {
 						this.render_contents();
+					});
+
 				},
 				render_contents: function() {
 					const container = dialog.domNode.querySelector(".contents");