有什么方法可以使用 Puppeteer 或 Chrome DevTools 来延迟 Chrome 响应负载？

Question

下面是我使用 PuppeteerSharp 库在 Chrome 浏览器中延迟请求的代码。

        public static void HandleRequestIntercepted(object sender, RequestEventArgs args)
        {
            Task.Run(async () => {
                await Task.Delay(1000);
                await args.Request.ContinueAsync();
            });
        }

        static void Main(string[] args)
        {
            Task.Run(async () =>
            {
                Browser b = await Puppeteer.LaunchAsync(new LaunchOptions()
                {
                    ExecutablePath = "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe",
                    DefaultViewport = null,
                    Headless = false
                });

                Page[] pages = await b.PagesAsync();
                Page page = pages[0];


                CDPSession cdpSession = await page.Target.CreateCDPSessionAsync();
                JObject obj = await cdpSession.SendAsync("Network.enable");
                await page.SetRequestInterceptionAsync(true);

                // Subscribe to requests
                page.Request += HandleRequestIntercepted;
            }
        }

但是，是否可以类似地延迟响应？具体来说，我希望 Chrome 将响应负载延迟 X 时间。

Answer 1

我能够使用以下代码引入响应延迟：

        public static CDPSession _cdpSessionResponse;

        public static void CdpSessionMessageReceived(object sender, MessageEventArgs args)
        {
            if (args.MessageID == "Fetch.requestPaused")
            {
                Task.Run(async () => 
                {
                    await Task.Delay(3000); // Wait 3 seconds
                    await _cdpSessionResponse.SendAsync("Fetch.continueRequest",
                        new Dictionary<string, object>
                        {
                            { "requestId", args.MessageData.ToObject<FetchRequestPausedResponse>().RequestId }
                        });
                });
            }
        }

        static void Main(string[] args)
        {
            Task.Run(async () =>
            {
                Browser b = await Puppeteer.LaunchAsync(new LaunchOptions()
                {
                    ExecutablePath = "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe",
                    DefaultViewport = null,
                    Headless = false
                });

                Page[] pages = await b.PagesAsync();
                Page page = pages[0];

               

                // Set up RESPONSE interception using PuppeteerSharp
                
                _cdpSessionResponse = await page.Target.CreateCDPSessionAsync();

                JObject response = await _cdpSessionResponse.SendAsync("Fetch.enable",
                    new Dictionary<string, object>
                    {
                        {
                            "patterns", new Dictionary<string, object>[]
                            {
                                new Dictionary<string, object>
                                {
                                    { "requestStage", "Response" }
                                }
                            }
                        }
                    });

                _cdpSessionResponse.MessageReceived += CdpSessionMessageReceived;
            }
        }

        internal class FetchRequestPausedResponse
        {
            public string RequestId { get; set; }

            public string NetworkId { get; set; }
        }

然而，这令人费解，因为这是我在 Chrome DevTools 网络选项卡中看到的内容——并非所有响应都被一条长蓝线延迟：

为了比较，如果我将行 { "requestStage", "Response" } 更改为 { "requestStage", "Request" }，我看到所有请求都被延迟了一条长透明线（排队时间）：

我不确定为什么会有这种差异 - 也许这是 Chrome DevTools 协议的内部原因？

有什么方法可以使用 Puppeteer 或 Chrome DevTools 来延迟 Chrome 响应负载？

Is there any way to delay a Chrome response payload using Puppeteer or Chrome DevTools?

google-chrome-devtools

puppeteer

puppeteer-sharp