Offcanvas: activate focustrap when backdrop is enabled (#36717)

* fix(offcanvas): activate focustrap when backdrop is enabled
* Adding tabindex='-1' for both offcanvases in the docs
* Remove useless aria-expanded='false' in togglers
* Update js/tests/unit/offcanvas.spec.js

Co-authored-by: Julien Déramond <julien.deramond@orange.com>
Co-authored-by: Julien Déramond <juderamond@gmail.com>
Co-authored-by: Patrick H. Lauke <redux@splintered.co.uk>

js/src/offcanvas.js

@@ -114,7 +114,7 @@ class Offcanvas extends BaseComponent {
     this._element.classList.add(CLASS_NAME_SHOWING)
 
     const completeCallBack = () => {
-      if (!this._config.scroll) {
+      if (!this._config.scroll || this._config.backdrop) {
         this._focustrap.activate()
       }
 

js/tests/unit/offcanvas.spec.js

@@ -293,7 +293,8 @@ describe('Offcanvas', () => {
 
         const offCanvasEl = fixtureEl.querySelector('.offcanvas')
         const offCanvas = new Offcanvas(offCanvasEl, {
-          scroll: true
+          scroll: true,
+          backdrop: false
         })
 
         const spy = spyOn(offCanvas._focustrap, 'activate').and.callThrough()
@@ -306,6 +307,27 @@ describe('Offcanvas', () => {
         offCanvas.show()
       })
     })
+
+    it('should trap focus if scroll is allowed OR backdrop is enabled', () => {
+      return new Promise(resolve => {
+        fixtureEl.innerHTML = '<div class="offcanvas"></div>'
+
+        const offCanvasEl = fixtureEl.querySelector('.offcanvas')
+        const offCanvas = new Offcanvas(offCanvasEl, {
+          scroll: true,
+          backdrop: true
+        })
+
+        const spy = spyOn(offCanvas._focustrap, 'activate').and.callThrough()
+
+        offCanvasEl.addEventListener('shown.bs.offcanvas', () => {
+          expect(spy).toHaveBeenCalled()
+          resolve()
+        })
+
+        offCanvas.show()
+      })
+    })
   })
 
   describe('toggle', () => {

site/layouts/_default/docs.html

@@ -1,7 +1,7 @@
 {{ define "main" }}
   <div class="container-xxl bd-gutter mt-3 my-md-4 bd-layout">
     <aside class="bd-sidebar">
-      <div class="offcanvas-lg offcanvas-start" id="bdSidebar" aria-labelledby="bdSidebarOffcanvasLabel">
+      <div class="offcanvas-lg offcanvas-start" tabindex="-1" id="bdSidebar" aria-labelledby="bdSidebarOffcanvasLabel">
         <div class="offcanvas-header border-bottom">
           <h5 class="offcanvas-title" id="bdSidebarOffcanvasLabel">Browse docs</h5>
           <button type="button" class="btn-close" data-bs-dismiss="offcanvas" aria-label="Close" data-bs-target="#bdSidebar"></button>

site/layouts/partials/docs-navbar.html

@@ -1,7 +1,7 @@
 <header class="navbar navbar-expand-lg navbar-dark bd-navbar sticky-top">
   <nav class="container-xxl bd-gutter flex-wrap flex-lg-nowrap" aria-label="Main navigation">
     {{- if eq .Layout "docs" }}
-      <button class="navbar-toggler p-2" type="button" data-bs-toggle="offcanvas" data-bs-target="#bdSidebar" aria-controls="bdSidebar" aria-expanded="false" aria-label="Toggle docs navigation">
+      <button class="navbar-toggler p-2" type="button" data-bs-toggle="offcanvas" data-bs-target="#bdSidebar" aria-controls="bdSidebar" aria-label="Toggle docs navigation">
         {{ partial "icons/hamburger.svg" (dict "class" "bi" "width" "24" "height" "24") }}
         <span class="d-none fs-6 pe-1">Browse</span>
       </button>
@@ -13,11 +13,11 @@
       {{ partial "icons/bootstrap-white-fill.svg" (dict "class" "d-block my-1" "width" "40" "height" "32") }}
     </a>
 
-    <button class="navbar-toggler d-flex d-lg-none order-3 p-2" type="button" data-bs-toggle="offcanvas" data-bs-target="#bdNavbar" aria-controls="bdNavbar" aria-expanded="false" aria-label="Toggle navigation">
+    <button class="navbar-toggler d-flex d-lg-none order-3 p-2" type="button" data-bs-toggle="offcanvas" data-bs-target="#bdNavbar" aria-controls="bdNavbar" aria-label="Toggle navigation">
       <svg class="bi" aria-hidden="true"><use xlink:href="#three-dots"></use></svg>
     </button>
 
-    <div class="offcanvas-lg offcanvas-end flex-grow-1" id="bdNavbar" aria-labelledby="bdNavbarOffcanvasLabel" data-bs-scroll="true">
+    <div class="offcanvas-lg offcanvas-end flex-grow-1" tabindex="-1" id="bdNavbar" aria-labelledby="bdNavbarOffcanvasLabel" data-bs-scroll="true">
       <div class="offcanvas-header px-4 pb-0">
         <h5 class="offcanvas-title text-white" id="bdNavbarOffcanvasLabel">Bootstrap</h5>
         <button type="button" class="btn-close btn-close-white" data-bs-dismiss="offcanvas" aria-label="Close" data-bs-target="#bdNavbar"></button>