feat: Rewrite keyboardEventListener mixin to a composable (#9831)

app/javascript/dashboard/components/ChatList.vue

@@ -1,14 +1,15 @@
 <script>
+import { ref } from 'vue';
 import { mapGetters } from 'vuex';
 import { useUISettings } from 'dashboard/composables/useUISettings';
 import { useAlert } from 'dashboard/composables';
+import { useKeyboardEvents } from 'dashboard/composables/useKeyboardEvents';
 import VirtualList from 'vue-virtual-scroll-list';
 
 import ChatListHeader from './ChatListHeader.vue';
 import ConversationAdvancedFilter from './widgets/conversation/ConversationAdvancedFilter.vue';
 import ChatTypeTabs from './widgets/ChatTypeTabs.vue';
 import ConversationItem from './ConversationItem.vue';
-import keyboardEventListenerMixins from 'shared/mixins/keyboardEventListenerMixins';
 import conversationMixin from '../mixins/conversations';
 import wootConstants from 'dashboard/constants/globals';
 import advancedFilterTypes from './widgets/conversation/advancedFilterItems';
@@ -41,7 +42,7 @@ export default {
     IntersectionObserver,
     VirtualList,
   },
-  mixins: [conversationMixin, keyboardEventListenerMixins, filterMixin],
+  mixins: [conversationMixin, filterMixin],
   provide() {
     return {
       // Actions to be performed on virtual list item and context menu.
@@ -89,8 +90,63 @@ export default {
   setup() {
     const { uiSettings } = useUISettings();
 
+    const conversationListRef = ref(null);
+
+    const getKeyboardListenerParams = () => {
+      const allConversations = conversationListRef.value.querySelectorAll(
+        'div.conversations-list div.conversation'
+      );
+      const activeConversation = conversationListRef.value.querySelector(
+        'div.conversations-list div.conversation.active'
+      );
+      const activeConversationIndex = [...allConversations].indexOf(
+        activeConversation
+      );
+      const lastConversationIndex = allConversations.length - 1;
+      return {
+        allConversations,
+        activeConversation,
+        activeConversationIndex,
+        lastConversationIndex,
+      };
+    };
+    const handlePreviousConversation = () => {
+      const { allConversations, activeConversationIndex } =
+        getKeyboardListenerParams();
+      if (activeConversationIndex === -1) {
+        allConversations[0].click();
+      }
+      if (activeConversationIndex >= 1) {
+        allConversations[activeConversationIndex - 1].click();
+      }
+    };
+    const handleNextConversation = () => {
+      const {
+        allConversations,
+        activeConversationIndex,
+        lastConversationIndex,
+      } = getKeyboardListenerParams();
+      if (activeConversationIndex === -1) {
+        allConversations[lastConversationIndex].click();
+      } else if (activeConversationIndex < lastConversationIndex) {
+        allConversations[activeConversationIndex + 1].click();
+      }
+    };
+    const keyboardEvents = {
+      'Alt+KeyJ': {
+        action: () => handlePreviousConversation(),
+        allowOnFocusedInput: true,
+      },
+      'Alt+KeyK': {
+        action: () => handleNextConversation(),
+        allowOnFocusedInput: true,
+      },
+    };
+    useKeyboardEvents(keyboardEvents, conversationListRef);
+
     return {
       uiSettings,
+      conversationListRef,
     };
   },
   data() {
@@ -113,7 +169,7 @@ export default {
       isContextMenuOpen: false,
       appliedFilter: [],
       infiniteLoaderOptions: {
-        root: this.$refs.conversationList,
+        root: this.$refs.conversationListRef,
         rootMargin: '100px 0px 100px 0px',
       },
 
@@ -490,58 +546,6 @@ export default {
         }))
       );
     },
-    getKeyboardListenerParams() {
-      const allConversations = this.$refs.conversationList.querySelectorAll(
-        'div.conversations-list div.conversation'
-      );
-      const activeConversation = this.$refs.conversationList.querySelector(
-        'div.conversations-list div.conversation.active'
-      );
-      const activeConversationIndex = [...allConversations].indexOf(
-        activeConversation
-      );
-      const lastConversationIndex = allConversations.length - 1;
-      return {
-        allConversations,
-        activeConversation,
-        activeConversationIndex,
-        lastConversationIndex,
-      };
-    },
-    handlePreviousConversation() {
-      const { allConversations, activeConversationIndex } =
-        this.getKeyboardListenerParams();
-      if (activeConversationIndex === -1) {
-        allConversations[0].click();
-      }
-      if (activeConversationIndex >= 1) {
-        allConversations[activeConversationIndex - 1].click();
-      }
-    },
-    handleNextConversation() {
-      const {
-        allConversations,
-        activeConversationIndex,
-        lastConversationIndex,
-      } = this.getKeyboardListenerParams();
-      if (activeConversationIndex === -1) {
-        allConversations[lastConversationIndex].click();
-      } else if (activeConversationIndex < lastConversationIndex) {
-        allConversations[activeConversationIndex + 1].click();
-      }
-    },
-    getKeyboardEvents() {
-      return {
-        'Alt+KeyJ': {
-          action: () => this.handlePreviousConversation(),
-          allowOnFocusedInput: true,
-        },
-        'Alt+KeyK': {
-          action: () => this.handleNextConversation(),
-          allowOnFocusedInput: true,
-        },
-      };
-    },
     resetAndFetchData() {
       this.appliedFilter = [];
       this.resetBulkActions();
@@ -927,7 +931,7 @@ export default {
       @assignTeam="onAssignTeamsForBulk"
     />
     <div
-      ref="conversationList"
+      ref="conversationListRef"
       class="flex-1 conversations-list"
       :class="{ 'overflow-hidden': isContextMenuOpen }"
     >

app/javascript/dashboard/components/layout/Sidebar.vue

@@ -1,11 +1,13 @@
 <script>
+import { ref } from 'vue';
 import { mapGetters } from 'vuex';
 import { getSidebarItems } from './config/default-sidebar';
+import { useKeyboardEvents } from 'dashboard/composables/useKeyboardEvents';
+import { useRoute, useRouter } from 'dashboard/composables/route';
 
 import PrimarySidebar from './sidebarComponents/Primary.vue';
 import SecondarySidebar from './sidebarComponents/Secondary.vue';
-import keyboardEventListenerMixins from 'shared/mixins/keyboardEventListenerMixins';
-import router, { routesWithPermissions } from '../../routes';
+import { routesWithPermissions } from '../../routes';
 import { hasPermissions } from '../../helper/permissionsHelper';
 
 export default {
@@ -13,7 +15,6 @@ export default {
     PrimarySidebar,
     SecondarySidebar,
   },
-  mixins: [keyboardEventListenerMixins],
   props: {
     showSecondarySidebar: {
       type: Boolean,
@@ -24,6 +25,52 @@ export default {
       default: '',
     },
   },
+  setup(props, { emit }) {
+    const sidebarRef = ref(null);
+    const route = useRoute();
+    const router = useRouter();
+
+    const toggleKeyShortcutModal = () => {
+      emit('openKeyShortcutModal');
+    };
+    const closeKeyShortcutModal = () => {
+      emit('closeKeyShortcutModal');
+    };
+    const isCurrentRouteSameAsNavigation = routeName => {
+      return route.name === routeName;
+    };
+    const navigateToRoute = routeName => {
+      if (!isCurrentRouteSameAsNavigation(routeName)) {
+        router.push({ name: routeName });
+      }
+    };
+    const keyboardEvents = {
+      '$mod+Slash': {
+        action: toggleKeyShortcutModal,
+      },
+      '$mod+Escape': {
+        action: closeKeyShortcutModal,
+      },
+      'Alt+KeyC': {
+        action: () => navigateToRoute('home'),
+      },
+      'Alt+KeyV': {
+        action: () => navigateToRoute('contacts_dashboard'),
+      },
+      'Alt+KeyR': {
+        action: () => navigateToRoute('account_overview_reports'),
+      },
+      'Alt+KeyS': {
+        action: () => navigateToRoute('agent_list'),
+      },
+    };
+    useKeyboardEvents(keyboardEvents, sidebarRef);
+
+    return {
+      toggleKeyShortcutModal,
+      sidebarRef,
+    };
+  },
   data() {
     return {
       showOptionsMenu: false,
@@ -131,38 +178,6 @@ export default {
         this.$store.dispatch('customViews/get', this.activeCustomView);
       }
     },
-    toggleKeyShortcutModal() {
-      this.$emit('openKeyShortcutModal');
-    },
-    closeKeyShortcutModal() {
-      this.$emit('closeKeyShortcutModal');
-    },
-    getKeyboardEvents() {
-      return {
-        '$mod+Slash': this.toggleKeyShortcutModal,
-        '$mod+Escape': this.closeKeyShortcutModal,
-        'Alt+KeyC': {
-          action: () => this.navigateToRoute('home'),
-        },
-        'Alt+KeyV': {
-          action: () => this.navigateToRoute('contacts_dashboard'),
-        },
-        'Alt+KeyR': {
-          action: () => this.navigateToRoute('account_overview_reports'),
-        },
-        'Alt+KeyS': {
-          action: () => this.navigateToRoute('agent_list'),
-        },
-      };
-    },
-    navigateToRoute(routeName) {
-      if (!this.isCurrentRouteSameAsNavigation(routeName)) {
-        router.push({ name: routeName });
-      }
-    },
-    isCurrentRouteSameAsNavigation(routeName) {
-      return this.$route.name === routeName;
-    },
     toggleSupportChatWindow() {
       window.$chatwoot.toggle();
     },
@@ -180,7 +195,7 @@ export default {
 </script>
 
 <template>
-  <aside class="flex h-full">
+  <aside ref="sidebarRef" class="flex h-full">
     <PrimarySidebar
       :logo-source="globalConfig.logoThumbnail"
       :installation-name="globalConfig.installationName"

app/javascript/dashboard/components/widgets/WootWriter/ReplyTopPanel.vue

@@ -1,18 +1,14 @@
 <script>
+import { ref } from 'vue';
+import { useKeyboardEvents } from 'dashboard/composables/useKeyboardEvents';
 import { REPLY_EDITOR_MODES, CHAR_LENGTH_WARNING } from './constants';
-import keyboardEventListenerMixins from 'shared/mixins/keyboardEventListenerMixins';
 export default {
   name: 'ReplyTopPanel',
-  mixins: [keyboardEventListenerMixins],
   props: {
     mode: {
       type: String,
       default: REPLY_EDITOR_MODES.REPLY,
     },
-    setReplyMode: {
-      type: Function,
-      default: () => {},
-    },
     isMessageLengthReachingThreshold: {
       type: Boolean,
       default: () => false,
@@ -26,6 +22,36 @@ export default {
       default: false,
     },
   },
+  setup(props, { emit }) {
+    const replyTopRef = ref(null);
+
+    const setReplyMode = mode => {
+      emit('setReplyMode', mode);
+    };
+    const handleReplyClick = () => {
+      setReplyMode(REPLY_EDITOR_MODES.REPLY);
+    };
+    const handleNoteClick = () => {
+      setReplyMode(REPLY_EDITOR_MODES.NOTE);
+    };
+    const keyboardEvents = {
+      'Alt+KeyP': {
+        action: () => handleNoteClick(),
+        allowOnFocusedInput: true,
+      },
+      'Alt+KeyL': {
+        action: () => handleReplyClick(),
+        allowOnFocusedInput: true,
+      },
+    };
+    useKeyboardEvents(keyboardEvents, replyTopRef);
+
+    return {
+      handleReplyClick,
+      handleNoteClick,
+      replyTopRef,
+    };
+  },
   computed: {
     replyButtonClass() {
       return {
@@ -46,31 +72,14 @@ export default {
         : `${this.charactersRemaining} ${CHAR_LENGTH_WARNING.UNDER_50}`;
     },
   },
-  methods: {
-    getKeyboardEvents() {
-      return {
-        'Alt+KeyP': {
-          action: () => this.handleNoteClick(),
-          allowOnFocusedInput: true,
-        },
-        'Alt+KeyL': {
-          action: () => this.handleReplyClick(),
-          allowOnFocusedInput: true,
-        },
-      };
-    },
-    handleReplyClick() {
-      this.setReplyMode(REPLY_EDITOR_MODES.REPLY);
-    },
-    handleNoteClick() {
-      this.setReplyMode(REPLY_EDITOR_MODES.NOTE);
-    },
-  },
 };
 </script>
 
 <template>
-  <div class="flex justify-between bg-black-50 dark:bg-slate-800">
+  <div
+    ref="replyTopRef"
+    class="flex justify-between bg-black-50 dark:bg-slate-800"
+  >
     <div class="button-group">
       <woot-button
         variant="clear"

app/javascript/dashboard/components/widgets/conversation/ReplyBox.vue

@@ -1091,10 +1091,10 @@ export default {
     />
     <ReplyTopPanel
       :mode="replyType"
-      :set-reply-mode="setReplyMode"
       :is-message-length-reaching-threshold="isMessageLengthReachingThreshold"
       :characters-remaining="charactersRemaining"
       :popout-reply-box="popoutReplyBox"
+      @setReplyMode="setReplyMode"
       @click="$emit('click')"
     />
     <ArticleSearchPopover

app/javascript/dashboard/composables/spec/useDetectKeyboardLayout.spec.js

@@ -0,0 +1,101 @@
+import { useDetectKeyboardLayout } from 'dashboard/composables/useDetectKeyboardLayout';
+import {
+  LAYOUT_QWERTY,
+  LAYOUT_QWERTZ,
+  LAYOUT_AZERTY,
+} from 'shared/helpers/KeyboardHelpers';
+
+describe('useDetectKeyboardLayout', () => {
+  beforeEach(() => {
+    window.cw_keyboard_layout = null;
+  });
+
+  it('returns cached layout if available', async () => {
+    window.cw_keyboard_layout = LAYOUT_QWERTY;
+    const layout = await useDetectKeyboardLayout();
+    expect(layout).toBe(LAYOUT_QWERTY);
+  });
+
+  it('should detect QWERTY layout using modern method', async () => {
+    navigator.keyboard = {
+      getLayoutMap: vi.fn().mockResolvedValue(
+        new Map([
+          ['KeyQ', 'q'],
+          ['KeyW', 'w'],
+          ['KeyE', 'e'],
+          ['KeyR', 'r'],
+          ['KeyT', 't'],
+          ['KeyY', 'y'],
+        ])
+      ),
+    };
+
+    const layout = await useDetectKeyboardLayout();
+    expect(layout).toBe(LAYOUT_QWERTY);
+  });
+
+  it('should detect QWERTZ layout using modern method', async () => {
+    navigator.keyboard = {
+      getLayoutMap: vi.fn().mockResolvedValue(
+        new Map([
+          ['KeyQ', 'q'],
+          ['KeyW', 'w'],
+          ['KeyE', 'e'],
+          ['KeyR', 'r'],
+          ['KeyT', 't'],
+          ['KeyY', 'z'],
+        ])
+      ),
+    };
+
+    const layout = await useDetectKeyboardLayout();
+    expect(layout).toBe(LAYOUT_QWERTZ);
+  });
+
+  it('should detect AZERTY layout using modern method', async () => {
+    navigator.keyboard = {
+      getLayoutMap: vi.fn().mockResolvedValue(
+        new Map([
+          ['KeyQ', 'a'],
+          ['KeyW', 'z'],
+          ['KeyE', 'e'],
+          ['KeyR', 'r'],
+          ['KeyT', 't'],
+          ['KeyY', 'y'],
+        ])
+      ),
+    };
+
+    const layout = await useDetectKeyboardLayout();
+    expect(layout).toBe(LAYOUT_AZERTY);
+  });
+
+  it('should use legacy method if navigator.keyboard is not available', async () => {
+    navigator.keyboard = undefined;
+
+    const layout = await useDetectKeyboardLayout();
+    expect([LAYOUT_QWERTY, LAYOUT_QWERTZ, LAYOUT_AZERTY]).toContain(layout);
+  });
+
+  it('should cache the detected layout', async () => {
+    navigator.keyboard = {
+      getLayoutMap: vi.fn().mockResolvedValue(
+        new Map([
+          ['KeyQ', 'q'],
+          ['KeyW', 'w'],
+          ['KeyE', 'e'],
+          ['KeyR', 'r'],
+          ['KeyT', 't'],
+          ['KeyY', 'y'],
+        ])
+      ),
+    };
+
+    const layout = await useDetectKeyboardLayout();
+    expect(layout).toBe(LAYOUT_QWERTY);
+
+    const layoutAgain = await useDetectKeyboardLayout();
+    expect(layoutAgain).toBe(LAYOUT_QWERTY);
+    expect(navigator.keyboard.getLayoutMap).toHaveBeenCalledTimes(1);
+  });
+});

app/javascript/dashboard/composables/spec/useKeyboardEvents.spec.js

@@ -0,0 +1,29 @@
+import { unref } from 'vue';
+import { useKeyboardEvents } from 'dashboard/composables/useKeyboardEvents';
+
+describe('useKeyboardEvents', () => {
+  it('should be defined', () => {
+    expect(useKeyboardEvents).toBeDefined();
+  });
+
+  it('should return a function', () => {
+    expect(useKeyboardEvents).toBeInstanceOf(Function);
+  });
+
+  it('should set up listeners on mount and remove them on unmount', async () => {
+    const el = document.createElement('div');
+    const elRef = unref({ value: el });
+    const events = {
+      'ALT+KeyL': () => {},
+    };
+
+    const mountedMock = vi.fn();
+    const unmountedMock = vi.fn();
+    useKeyboardEvents(events, elRef);
+    mountedMock();
+    unmountedMock();
+
+    expect(mountedMock).toHaveBeenCalled();
+    expect(unmountedMock).toHaveBeenCalled();
+  });
+});

app/javascript/dashboard/composables/useDetectKeyboardLayout.js

@@ -0,0 +1,73 @@
+import {
+  LAYOUT_QWERTY,
+  LAYOUT_QWERTZ,
+  LAYOUT_AZERTY,
+} from 'shared/helpers/KeyboardHelpers';
+
+/**
+ * Detects the keyboard layout using a legacy method by creating a hidden input and dispatching a key event.
+ * @returns {Promise<string>} A promise that resolves to the detected keyboard layout.
+ */
+async function detectLegacy() {
+  const input = document.createElement('input');
+  input.style.position = 'fixed';
+  input.style.top = '-100px';
+  document.body.appendChild(input);
+  input.focus();
+
+  return new Promise(resolve => {
+    const keyboardEvent = new KeyboardEvent('keypress', {
+      key: 'y',
+      keyCode: 89,
+      which: 89,
+      bubbles: true,
+      cancelable: true,
+    });
+
+    const handler = e => {
+      document.body.removeChild(input);
+      document.removeEventListener('keypress', handler);
+      if (e.key === 'z') {
+        resolve(LAYOUT_QWERTY);
+      } else if (e.key === 'y') {
+        resolve(LAYOUT_QWERTZ);
+      } else {
+        resolve(LAYOUT_AZERTY);
+      }
+    };
+
+    document.addEventListener('keypress', handler);
+    input.dispatchEvent(keyboardEvent);
+  });
+}
+
+/**
+ * Detects the keyboard layout using the modern navigator.keyboard API.
+ * @returns {Promise<string>} A promise that resolves to the detected keyboard layout.
+ */
+async function detect() {
+  const map = await navigator.keyboard.getLayoutMap();
+  const q = map.get('KeyQ');
+  const w = map.get('KeyW');
+  const e = map.get('KeyE');
+  const r = map.get('KeyR');
+  const t = map.get('KeyT');
+  const y = map.get('KeyY');
+
+  return [q, w, e, r, t, y].join('').toUpperCase();
+}
+
+/**
+ * Uses either the modern or legacy method to detect the keyboard layout, caching the result.
+ * @returns {Promise<string>} A promise that resolves to the detected keyboard layout.
+ */
+export async function useDetectKeyboardLayout() {
+  const cachedLayout = window.cw_keyboard_layout;
+  if (cachedLayout) {
+    return cachedLayout;
+  }
+
+  const layout = navigator.keyboard ? await detect() : await detectLegacy();
+  window.cw_keyboard_layout = layout;
+  return layout;
+}

app/javascript/dashboard/composables/useKeyboardEvents.js

@@ -0,0 +1,115 @@
+import { onMounted, onBeforeUnmount, unref } from 'vue';
+import {
+  isActiveElementTypeable,
+  isEscape,
+  keysToModifyInQWERTZ,
+  LAYOUT_QWERTZ,
+} from 'shared/helpers/KeyboardHelpers';
+import { useDetectKeyboardLayout } from 'dashboard/composables/useDetectKeyboardLayout';
+import { createKeybindingsHandler } from 'tinykeys';
+
+const keyboardListenerMap = new WeakMap();
+
+/**
+ * Determines if the keyboard event should be ignored based on the element type and handler settings.
+ * @param {Event} e - The event object.
+ * @param {Object|Function} handler - The handler configuration or function.
+ * @returns {boolean} - True if the event should be ignored, false otherwise.
+ */
+const shouldIgnoreEvent = (e, handler) => {
+  const isTypeable = isActiveElementTypeable(e);
+  const allowOnFocusedInput =
+    typeof handler === 'function' ? false : handler.allowOnFocusedInput;
+
+  if (isTypeable) {
+    if (isEscape(e)) {
+      e.target.blur();
+    }
+    return !allowOnFocusedInput;
+  }
+  return false;
+};
+
+/**
+ * Wraps the event handler to include custom logic before executing the handler.
+ * @param {Function} handler - The original event handler.
+ * @returns {Function} - The wrapped handler.
+ */
+const keydownWrapper = handler => {
+  return e => {
+    if (shouldIgnoreEvent(e, handler)) return;
+    //  extract the action to perform from the handler
+
+    const actionToPerform =
+      typeof handler === 'function' ? handler : handler.action;
+    actionToPerform(e);
+  };
+};
+
+/**
+ * Wraps all provided keyboard events in handlers that respect the current keyboard layout.
+ * @param {Object} events - The object containing event names and their handlers.
+ * @returns {Object} - The object with event names possibly modified based on the keyboard layout and wrapped handlers.
+ */
+async function wrapEventsInKeybindingsHandler(events) {
+  const wrappedEvents = {};
+  const currentLayout = await useDetectKeyboardLayout();
+
+  Object.keys(events).forEach(originalEventName => {
+    const modifiedEventName =
+      currentLayout === LAYOUT_QWERTZ &&
+      keysToModifyInQWERTZ.has(originalEventName)
+        ? `Shift+${originalEventName}`
+        : originalEventName;
+
+    wrappedEvents[modifiedEventName] = keydownWrapper(
+      events[originalEventName]
+    );
+  });
+  return wrappedEvents;
+}
+
+/**
+ * Sets up keyboard event listeners on the specified element.
+ * @param {Element} root - The DOM element to attach listeners to.
+ * @param {Object} events - The events to listen for.
+ */
+const setupListeners = (root, events) => {
+  if (root instanceof Element && events) {
+    const keydownHandler = createKeybindingsHandler(events);
+    const handler = window.addEventListener('keydown', keydownHandler);
+    keyboardListenerMap.set(root, handler);
+  }
+};
+
+/**
+ * Removes keyboard event listeners from the specified element.
+ * @param {Element} root - The DOM element to remove listeners from.
+ */
+const removeListeners = root => {
+  if (root instanceof Element) {
+    const handlerToRemove = keyboardListenerMap.get(root);
+    document.removeEventListener('keydown', handlerToRemove);
+    keyboardListenerMap.delete(root);
+  }
+};
+
+/**
+ * Vue composable to handle keyboard events with support for different keyboard layouts.
+ * @param {Object} keyboardEvents - The keyboard events to handle.
+ * @param {ref} elRef - A Vue ref to the element to attach the keyboard events to.
+ */
+export function useKeyboardEvents(keyboardEvents, elRef = null) {
+  onMounted(async () => {
+    const el = unref(elRef);
+    const getKeyboardEvents = () => keyboardEvents || null;
+    const events = getKeyboardEvents();
+    const wrappedEvents = await wrapEventsInKeybindingsHandler(events);
+    setupListeners(el, wrappedEvents);
+  });
+
+  onBeforeUnmount(() => {
+    const el = unref(elRef);
+    removeListeners(el);
+  });
+}

app/javascript/shared/helpers/KeyboardHelpers.js

@@ -22,6 +22,14 @@ export const hasPressedCommandAndEnter = e => {
   return hasPressedCommand(e) && isEnter(e);
 };
 
+// If layout is QWERTZ then we add the Shift+keysToModify to fix an known issue
+// https://github.com/chatwoot/chatwoot/issues/9492
+export const keysToModifyInQWERTZ = new Set(['Alt+KeyP', 'Alt+KeyL']);
+
+export const LAYOUT_QWERTY = 'QWERTY';
+export const LAYOUT_QWERTZ = 'QWERTZ';
+export const LAYOUT_AZERTY = 'AZERTY';
+
 /**
  * Determines whether the active element is typeable.
  *