Merge pull request #19612 from atom/debounce-resize-event

Debounce the resize event handler

spec/window-event-handler-spec.js

@@ -1,5 +1,6 @@
 const KeymapManager = require('atom-keymap');
 const WindowEventHandler = require('../src/window-event-handler');
+const { conditionPromise } = require('./async-spec-helpers');
 
 describe('WindowEventHandler', () => {
   let windowEventHandler;
@@ -50,10 +51,13 @@ describe('WindowEventHandler', () => {
   });
 
   describe('resize event', () =>
-    it('calls storeWindowDimensions', () => {
+    it('calls storeWindowDimensions', async () => {
+      jasmine.useRealClock();
+
       spyOn(atom, 'storeWindowDimensions');
       window.dispatchEvent(new CustomEvent('resize'));
-      expect(atom.storeWindowDimensions).toHaveBeenCalled();
+
+      await conditionPromise(() => atom.storeWindowDimensions.callCount > 0);
     }));
 
   describe('window:close event', () =>

src/window-event-handler.js

@@ -1,5 +1,6 @@
 const { Disposable, CompositeDisposable } = require('event-kit');
 const listen = require('./delegated-listener');
+const { debounce } = require('underscore-plus');
 
 // Handles low-level events related to the `window`.
 module.exports = class WindowEventHandler {
@@ -65,7 +66,11 @@ module.exports = class WindowEventHandler {
     );
     this.addEventListener(this.window, 'focus', this.handleWindowFocus);
     this.addEventListener(this.window, 'blur', this.handleWindowBlur);
-    this.addEventListener(this.window, 'resize', this.handleWindowResize);
+    this.addEventListener(
+      this.window,
+      'resize',
+      debounce(this.handleWindowResize, 500)
+    );
 
     this.addEventListener(this.document, 'keyup', this.handleDocumentKeyEvent);
     this.addEventListener(