Feat: add resize handler to Offcanvas.js.

If we could use as default the `.offcanvas` class without modifiers, we then, could add a simplified selector
The selector itself, ignores the .offcanvas class as it doesn't have any responsive behavior
The `aria-modal` addon is to protect us, selection backdrop elements

js/src/offcanvas.js

@@ -41,6 +41,7 @@ const EVENT_SHOWN = `shown${EVENT_KEY}`
 const EVENT_HIDE = `hide${EVENT_KEY}`
 const EVENT_HIDE_PREVENTED = `hidePrevented${EVENT_KEY}`
 const EVENT_HIDDEN = `hidden${EVENT_KEY}`
+const EVENT_RESIZE = `resize${EVENT_KEY}`
 const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
 const EVENT_KEYDOWN_DISMISS = `keydown.dismiss${EVENT_KEY}`
 
@@ -205,14 +206,6 @@ class Offcanvas extends BaseComponent {
 
       this.hide()
     })
-
-    EventHandler.on(window, 'resize', () => {
-      // Add this check to help js be aligned with css changes on responsive offcanvas
-      if (this._isShown && getComputedStyle(this._element).position !== 'fixed') {
-        // this._backdrop.hide()
-        this.hide()
-      }
-    })
   }
 
   // Static
@@ -271,6 +264,14 @@ EventHandler.on(window, EVENT_LOAD_DATA_API, () => {
   }
 })
 
+EventHandler.on(window, EVENT_RESIZE, () => {
+  for (const element of SelectorEngine.find('[aria-modal][class*=show][class*=offcanvas-]')) {
+    if (getComputedStyle(element).position !== 'fixed') {
+      Offcanvas.getOrCreateInstance(element).hide()
+    }
+  }
+})
+
 enableDismissTrigger(Offcanvas)
 
 /**

js/tests/unit/offcanvas.spec.js

@@ -155,6 +155,28 @@ describe('Offcanvas', () => {
         offCanvas.show()
       })
     })
+
+    it('should call `hide` on resize, if element\'s position is not fixed any more', () => {
+      return new Promise(resolve => {
+        fixtureEl.innerHTML = '<div class="offcanvas-lg"></div>'
+
+        const offCanvasEl = fixtureEl.querySelector('div')
+        const offCanvas = new Offcanvas(offCanvasEl)
+
+        spyOn(offCanvas, 'hide').and.callThrough()
+
+        offCanvasEl.addEventListener('shown.bs.offcanvas', () => {
+          const resizeEvent = createEvent('resize')
+          offCanvasEl.style.removeProperty('position')
+
+          window.dispatchEvent(resizeEvent)
+          expect(offCanvas.hide).toHaveBeenCalled()
+          resolve()
+        })
+
+        offCanvas.show()
+      })
+    })
   })
 
   describe('config', () => {