Improve accessibility of modal dialogs (#974)

* improve details modal accessibility

* improve tag modal accessibility

* fix overlays in archive and shared pages

* update tests

* use buttons for closing dialogs

* replace description list

* hide preview image from screen readers

* update tests

bookmarks/frontend/behaviors/details-modal.js

@@ -1,61 +1,28 @@
-import { Behavior, registerBehavior } from "./index";
+import { registerBehavior } from "./index";
+import { isKeyboardActive } from "./focus-utils";
+import { ModalBehavior } from "./modal";
 
-class DetailsModalBehavior extends Behavior {
-  constructor(element) {
-    super(element);
+class DetailsModalBehavior extends ModalBehavior {
+  doClose() {
+    super.doClose();
 
-    this.onClose = this.onClose.bind(this);
-    this.onKeyDown = this.onKeyDown.bind(this);
+    // Navigate to close URL
+    const closeUrl = this.element.dataset.closeUrl;
+    Turbo.visit(closeUrl, {
+      action: "replace",
+      frame: "details-modal",
+    });
 
-    this.overlayLink = element.querySelector("a:has(.modal-overlay)");
-    this.buttonLink = element.querySelector("a:has(button.close)");
+    // Try restore focus to view details to view details link of respective bookmark
+    const bookmarkId = this.element.dataset.bookmarkId;
+    const restoreFocusElement =
+      document.querySelector(
+        `ul.bookmark-list li[data-bookmark-id='${bookmarkId}'] a.view-action`,
+      ) ||
+      document.querySelector("ul.bookmark-list") ||
+      document.body;
 
-    this.overlayLink.addEventListener("click", this.onClose);
-    this.buttonLink.addEventListener("click", this.onClose);
-    document.addEventListener("keydown", this.onKeyDown);
-  }
-
-  destroy() {
-    this.overlayLink.removeEventListener("click", this.onClose);
-    this.buttonLink.removeEventListener("click", this.onClose);
-    document.removeEventListener("keydown", this.onKeyDown);
-  }
-
-  onKeyDown(event) {
-    // Skip if event occurred within an input element
-    const targetNodeName = event.target.nodeName;
-    const isInputTarget =
-      targetNodeName === "INPUT" ||
-      targetNodeName === "SELECT" ||
-      targetNodeName === "TEXTAREA";
-
-    if (isInputTarget) {
-      return;
-    }
-
-    if (event.key === "Escape") {
-      this.onClose(event);
-    }
-  }
-
-  onClose(event) {
-    event.preventDefault();
-    this.element.classList.add("closing");
-    this.element.addEventListener(
-      "animationend",
-      (event) => {
-        if (event.animationName === "fade-out") {
-          this.element.remove();
-
-          const closeUrl = this.overlayLink.href;
-          Turbo.visit(closeUrl, {
-            action: "replace",
-            frame: "details-modal",
-          });
-        }
-      },
-      { once: true },
-    );
+    restoreFocusElement.focus({ focusVisible: isKeyboardActive() });
   }
 }
 

bookmarks/frontend/behaviors/focus-utils.js

@@ -0,0 +1,59 @@
+let keyboardActive = false;
+
+window.addEventListener(
+  "keydown",
+  () => {
+    keyboardActive = true;
+  },
+  { capture: true },
+);
+
+window.addEventListener(
+  "mousedown",
+  () => {
+    keyboardActive = false;
+  },
+  { capture: true },
+);
+
+export function isKeyboardActive() {
+  return keyboardActive;
+}
+
+export class FocusTrapController {
+  constructor(element) {
+    this.element = element;
+    this.focusableElements = this.element.querySelectorAll(
+      'a[href]:not([disabled]), button:not([disabled]), textarea:not([disabled]), input[type="text"]:not([disabled]), input[type="radio"]:not([disabled]), input[type="checkbox"]:not([disabled]), select:not([disabled])',
+    );
+    this.firstFocusableElement = this.focusableElements[0];
+    this.lastFocusableElement =
+      this.focusableElements[this.focusableElements.length - 1];
+
+    this.onKeyDown = this.onKeyDown.bind(this);
+
+    this.firstFocusableElement.focus({ focusVisible: keyboardActive });
+    this.element.addEventListener("keydown", this.onKeyDown);
+  }
+
+  destroy() {
+    this.element.removeEventListener("keydown", this.onKeyDown);
+  }
+
+  onKeyDown(event) {
+    if (event.key !== "Tab") {
+      return;
+    }
+    if (event.shiftKey) {
+      if (document.activeElement === this.firstFocusableElement) {
+        event.preventDefault();
+        this.lastFocusableElement.focus();
+      }
+    } else {
+      if (document.activeElement === this.lastFocusableElement) {
+        event.preventDefault();
+        this.firstFocusableElement.focus();
+      }
+    }
+  }
+}

bookmarks/frontend/behaviors/modal.js

@@ -0,0 +1,83 @@
+import { Behavior } from "./index";
+import { FocusTrapController } from "./focus-utils";
+
+export class ModalBehavior extends Behavior {
+  constructor(element) {
+    super(element);
+
+    this.onClose = this.onClose.bind(this);
+    this.onKeyDown = this.onKeyDown.bind(this);
+
+    this.overlay = element.querySelector(".modal-overlay");
+    this.closeButton = element.querySelector(".modal-header .close");
+
+    this.overlay.addEventListener("click", this.onClose);
+    this.closeButton.addEventListener("click", this.onClose);
+    document.addEventListener("keydown", this.onKeyDown);
+
+    this.setupInert();
+    this.focusTrap = new FocusTrapController(
+      element.querySelector(".modal-container"),
+    );
+  }
+
+  destroy() {
+    this.overlay.removeEventListener("click", this.onClose);
+    this.closeButton.removeEventListener("click", this.onClose);
+    document.removeEventListener("keydown", this.onKeyDown);
+
+    this.clearInert();
+    this.focusTrap.destroy();
+  }
+
+  setupInert() {
+    // Inert all other elements on the page
+    document
+      .querySelectorAll("body > *:not(.modals)")
+      .forEach((el) => el.setAttribute("inert", ""));
+  }
+
+  clearInert() {
+    // Clear inert attribute from all elements to allow focus outside the modal again
+    document
+      .querySelectorAll("body > *")
+      .forEach((el) => el.removeAttribute("inert"));
+  }
+
+  onKeyDown(event) {
+    // Skip if event occurred within an input element
+    const targetNodeName = event.target.nodeName;
+    const isInputTarget =
+      targetNodeName === "INPUT" ||
+      targetNodeName === "SELECT" ||
+      targetNodeName === "TEXTAREA";
+
+    if (isInputTarget) {
+      return;
+    }
+
+    if (event.key === "Escape") {
+      this.onClose(event);
+    }
+  }
+
+  onClose(event) {
+    event.preventDefault();
+    this.element.classList.add("closing");
+    this.element.addEventListener(
+      "animationend",
+      (event) => {
+        if (event.animationName === "fade-out") {
+          this.doClose();
+        }
+      },
+      { once: true },
+    );
+  }
+
+  doClose() {
+    this.element.remove();
+    this.clearInert();
+    this.element.dispatchEvent(new CustomEvent("modal:close"));
+  }
+}

bookmarks/frontend/behaviors/tag-modal.js

@@ -1,29 +1,31 @@
 import { Behavior, registerBehavior } from "./index";
+import { ModalBehavior } from "./modal";
+import { isKeyboardActive } from "./focus-utils";
 
-class TagModalBehavior extends Behavior {
+class TagModalTriggerBehavior extends Behavior {
   constructor(element) {
     super(element);
 
     this.onClick = this.onClick.bind(this);
-    this.onClose = this.onClose.bind(this);
 
     element.addEventListener("click", this.onClick);
   }
 
   destroy() {
-    this.onClose();
     this.element.removeEventListener("click", this.onClick);
   }
 
   onClick() {
+    // Creates a new modal and teleports the tag cloud into it
     const modal = document.createElement("div");
     modal.classList.add("modal", "active");
+    modal.setAttribute("ld-tag-modal", "");
     modal.innerHTML = `
-      <div class="modal-overlay" aria-label="Close"></div>
-      <div class="modal-container">
+      <div class="modal-overlay"></div>
+      <div class="modal-container" role="dialog" aria-modal="true">
         <div class="modal-header">
           <h2>Tags</h2>
-          <button class="close" aria-label="Close">
+          <button class="close" aria-label="Close dialog">
             <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" stroke-width="2"
                  stroke="currentColor" fill="none" stroke-linecap="round" stroke-linejoin="round">
               <path stroke="none" d="M0 0h24v24H0z" fill="none"></path>
@@ -37,32 +39,38 @@ class TagModalBehavior extends Behavior {
         </div>
       </div>    
     `;
+    modal.addEventListener("modal:close", this.onClose);
 
-    const tagCloud = document.querySelector(".tag-cloud");
-    const tagCloudContainer = tagCloud.parentElement;
+    modal.tagCloud = document.querySelector(".tag-cloud");
+    modal.tagCloudContainer = modal.tagCloud.parentElement;
 
     const content = modal.querySelector(".content");
-    content.appendChild(tagCloud);
+    content.appendChild(modal.tagCloud);
 
-    const overlay = modal.querySelector(".modal-overlay");
-    const closeButton = modal.querySelector(".close");
-    overlay.addEventListener("click", this.onClose);
-    closeButton.addEventListener("click", this.onClose);
-
-    this.modal = modal;
-    this.tagCloud = tagCloud;
-    this.tagCloudContainer = tagCloudContainer;
-    document.body.appendChild(modal);
-  }
-
-  onClose() {
-    if (!this.modal) {
-      return;
-    }
-
-    this.modal.remove();
-    this.tagCloudContainer.appendChild(this.tagCloud);
+    document.body.querySelector(".modals").appendChild(modal);
   }
 }
 
+class TagModalBehavior extends ModalBehavior {
+  destroy() {
+    super.destroy();
+    // Always close on destroy to restore tag cloud to original parent before
+    // turbo caches DOM
+    this.doClose();
+  }
+
+  doClose() {
+    super.doClose();
+
+    // Restore tag cloud to original parent
+    this.element.tagCloudContainer.appendChild(this.element.tagCloud);
+
+    // Try restore focus to tag cloud trigger
+    const restoreFocusElement =
+      document.querySelector("[ld-tag-modal-trigger]") || document.body;
+    restoreFocusElement.focus({ focusVisible: isKeyboardActive() });
+  }
+}
+
+registerBehavior("ld-tag-modal-trigger", TagModalTriggerBehavior);
 registerBehavior("ld-tag-modal", TagModalBehavior);