chrome-devtools-frontend/front_end/panels/timeline/components/insights/RenderBlocking.ts

Chrome DevTools UI

// Copyright 2024 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import './Table.js';

import * as i18n from '../../../../core/i18n/i18n.js';
import * as Platform from '../../../../core/platform/platform.js';
import type {RenderBlockingInsightModel} from '../../../../models/trace/insights/RenderBlocking.js';
import * as Trace from '../../../../models/trace/trace.js';
import * as Lit from '../../../../ui/lit/lit.js';
import type * as Overlays from '../../overlays/overlays.js';

import {BaseInsightComponent} from './BaseInsightComponent.js';
import {eventRef} from './EventRef.js';

const {UIStrings, i18nString} = Trace.Insights.Models.RenderBlocking;

const {html} = Lit;

export class RenderBlocking extends BaseInsightComponent<RenderBlockingInsightModel> {
  static override readonly litTagName = Lit.StaticHtml.literal`devtools-performance-render-blocking-requests`;
  override internalName: string = 'render-blocking-requests';

  override createOverlays(): Overlays.Overlays.TimelineOverlay[] {
    if (!this.model) {
      return [];
    }

    return this.model.renderBlockingRequests.map(request => this.#createOverlayForRequest(request));
  }

  #createOverlayForRequest(request: Trace.Types.Events.SyntheticNetworkRequest): Overlays.Overlays.EntryOutline {
    return {
      type: 'ENTRY_OUTLINE',
      entry: request,
      outlineReason: 'ERROR',
    };
  }

  override getEstimatedSavingsTime(): Trace.Types.Timing.Milli|null {
    return this.model?.metricSavings?.FCP ?? null;
  }

  override renderContent(): Lit.LitTemplate {
    if (!this.model) {
      return Lit.nothing;
    }

    const MAX_REQUESTS = 3;
    const topRequests = this.model.renderBlockingRequests.slice(0, MAX_REQUESTS);

    if (!topRequests.length) {
      return html`<div class="insight-section">${i18nString(UIStrings.noRenderBlocking)}</div>`;
    }

    // clang-format off
    return html`
      <div class="insight-section">
        <devtools-performance-table
          .data=${{
            insight: this,
            headers: [i18nString(UIStrings.renderBlockingRequest), i18nString(UIStrings.duration)],
            rows: topRequests.map(request => ({
              values: [
                eventRef(request),
                i18n.TimeUtilities.millisToString(Platform.Timing.microSecondsToMilliSeconds(request.dur)),
              ],
              overlays: [this.#createOverlayForRequest(request)],
            })),
          }}>
        </devtools-performance-table>
      </div>
    `;
    // clang-format on
  }
}

declare global {
  interface HTMLElementTagNameMap {
    'devtools-performance-render-blocking-requests': RenderBlocking;
  }
}

customElements.define('devtools-performance-render-blocking-requests', RenderBlocking);