trilium/src/public/app/widgets/tab_caching_widget.js

import TabAwareWidget from "./tab_aware_widget.js";
import keyboardActionsService from "../services/keyboard_actions.js";

export default class TabCachingWidget extends TabAwareWidget {
    constructor(widgetFactory) {
        super();

        this.widgetFactory = widgetFactory;
        this.widgets = {};
    }

    doRender() {
        return this.$widget = $(`<div class="marker" style="display: none;">`);
    }

    async newTabOpenedEvent({tabContext}) {
        const {tabId} = tabContext;

        if (this.widgets[tabId]) {
            return;
        }

        this.widgets[tabId] = this.widgetFactory();

        const $renderedWidget = this.widgets[tabId].render();
        this.widgets[tabId].toggleExt(false); // new tab is always not active, can be activated after creation

        this.$widget.after($renderedWidget);

        keyboardActionsService.updateDisplayedShortcuts($renderedWidget);

        await this.widgets[tabId].handleEvent('setTabContext', {tabContext});

        this.child(this.widgets[tabId]); // add as child only once it is ready (rendered with tabContext)
    }

    tabRemovedEvent({tabId}) {
        const widget = this.widgets[tabId];

        if (widget) {
            widget.remove();
            delete this.widgets[tabId];

            this.children = this.children.filter(ch => ch !== widget);
        }
    }

    async refresh() {
        this.toggleExt(true);
    }

    toggleInt(show) {} // not needed

    toggleExt(show) {
        for (const tabId in this.widgets) {
            this.widgets[tabId].toggleExt(show && this.isTab(tabId));
        }
    }

    /**
     * widget.hasBeenAlreadyShown is intended for lazy loading of cached tabs - initial note switches of new tabs
     * are not executed, we're waiting for the first tab activation and then we update the tab. After this initial
     * activation further note switches are always propagated to the tabs.
     */
    handleEventInChildren(name, data) {
        if (['tabNoteSwitched', 'tabNoteSwitchedAndActivated'].includes(name)) {
            // this event is propagated only to the widgets of a particular tab
            const widget = this.widgets[data.tabContext.tabId];

            if (widget && (widget.hasBeenAlreadyShown || name === 'tabNoteSwitchedAndActivated')) {
                widget.hasBeenAlreadyShown = true;

                return widget.handleEvent('tabNoteSwitched', data);
            }
            else {
                return Promise.resolve();
            }
        }

        if (name === 'activeTabChanged') {
            const widget = this.widgets[data.tabContext.tabId];

            if (widget.hasBeenAlreadyShown) {
                return Promise.resolve();
            }
            else {
                widget.hasBeenAlreadyShown = true;

                return widget.handleEvent(name, data);
            }
        } else {
            return super.handleEventInChildren(name, data);
        }
    }
}