chrome-devtools-frontend/front_end/core/platform/api/HostRuntime.ts

Chrome DevTools UI

// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

export interface ScreenshotOptions {
  base64Png: string;
  fileName: string;
  clip?: {
    screenRectWidth: number,
    screenRectHeight: number,
    visiblePageRectLeft: number,
    visiblePageRectTop: number,
  };
}

export interface CacheEntry {
  put(url: string, response: Response): Promise<void>;
  match(url: string): Promise<Response|undefined>;
}

export interface CacheStorageLike {
  open(name: string): Promise<CacheEntry>;
  delete(name: string): Promise<boolean>;
}

/**
 * Provides abstractions for host features that require different implementations depending
 * on whether DevTools runs in the browser or Node.js
 */
export interface HostRuntime {
  createWorker(url: string): Worker;
  workerScope: WorkerScope;
  getOnLine(): boolean;
  getUserAgent(): string;
  getLocalStorage(): Storage|undefined;
  getCacheStorage(): CacheStorageLike|undefined;
  getDevicePixelRatio(): number;
  saveScreenshot(options: ScreenshotOptions): Promise<void>;
  revokeLastScreenshotUrl(): void;
  loadTextFile(url: URL): Promise<string>;
  evaluateCSS(dataValue: string|null, customExpr: string): string|null;
  removeCSSEvaluationElement(): void;
}

/**
 * Abstracts away the differences between browser web workers and Node.js worker threads.
 */
export interface Worker {
  postMessage(message: unknown, transfer?: WorkerTransferable[]): void;

  dispose(): void;
  terminate(immediately?: boolean): void;

  set onmessage(listener: (event: WorkerMessageEvent) => void);
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  set onerror(listener: (event: any) => void);
}

export type WorkerMessagePort = typeof MessagePort.prototype;

/**
 * Currently we only transfer MessagePorts to workers, but it's possible to add
 * more things (like ReadableStream) as long as it's present in all runtimes.
 */
export type WorkerTransferable = WorkerMessagePort;

/**
 * Used by workers to communicate with their parent.
 */
export interface WorkerScope {
  postMessage(message: unknown, transfer?: WorkerTransferable[]): void;
  set onmessage(listener: (event: WorkerMessageEvent) => Promise<void>| void);
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export interface WorkerMessageEvent<T = any> {
  readonly data: T;
  ports: readonly WorkerMessagePort[];
}