Question

我想在Windows窗体中使用JavaScript执行CefSharp代码，但它不起作用。代码如下，并且未显示消息test。我错过了什么吗？

var browser = new ChromiumWebBrowser("http://localhost:50056/simple.aspx");
browser.Name = "Simple Page";
browser.Dock = DockStyle.Fill;            
this.Controls.Add(browser);
browser.ExecuteScriptAsync("alert('test');");

Answer 1

在执行JavaScript之前，您必须等待浏览器充分加载。开始尝试访问OnFrameLoadStart中的DOM很有诱惑力，而V8Context已经创建，您将能够执行DOM未完成加载的脚本。如果您需要尽可能早地访问DOM，那么订阅DOMContentLoaded，执行JavaScript的一些示例如下

browser.RenderProcessMessageHandler = new RenderProcessMessageHandler();

public class RenderProcessMessageHandler : IRenderProcessMessageHandler
{
  // Wait for the underlying JavaScript Context to be created. This is only called for the main frame.
  // If the page has no JavaScript, no context will be created.
  void IRenderProcessMessageHandler.OnContextCreated(IWebBrowser browserControl, IBrowser browser, IFrame frame)
  {
    const string script = "document.addEventListener('DOMContentLoaded', function(){ alert('DomLoaded'); });";

    frame.ExecuteJavaScriptAsync(script);
  }
}

//Wait for the page to finish loading (all resources will have been loaded, rendering is likely still happening)
browser.LoadingStateChanged += (sender, args) =>
{
  //Wait for the Page to finish loading
  if (args.IsLoading == false)
  {
    browser.ExecuteJavaScriptAsync("alert('All Resources Have Loaded');");
  }
}

//Wait for the MainFrame to finish loading
browser.FrameLoadEnd += (sender, args) =>
{
  //Wait for the MainFrame to finish loading
  if(args.Frame.IsMain)
  {
    args.Frame.ExecuteJavaScriptAsync("alert('MainFrame finished loading');");
  }
};

Answer 2

我认为，在调用存在于 HTML 中的 JavaScript 函数并传递输入参数的情况下，可以简单地使用 MainWindow 构造函数中的 Browser.LoadingStateChanged 事件来确保启动加载。此事件将在声明 HTML 文件的 Browser_Loaded 之后调用。以下是代码示例：

public MainWindow()
        {
            InitializeComponent();

            //Wait for the page to finish loading (all resources will have been loaded, rendering is likely still happening)
            Browser.LoadingStateChanged += (sender, args) =>
            {
                //Wait for the Page to finish loading
                if (args.IsLoading == false)
                {
                    Browser.ExecuteScriptAsync("JavaScripFunctionName1", new object[] { arg1, arg2});
                }
            };
        }

private void Browser_Loaded(object sender, RoutedEventArgs e)
        {
            Browser.LoadHtml(File.ReadAllText(GetFilePath("YourHTMLFileName.html")));
        }

但是，如果您想执行 JavaScript 代码并获得结果，您应该使用：

var result = await Browser.EvaluateScriptAsync("JavaScripFunctionName2", new object[] { });
MessageBox.Show(result.Result.ToString());

在 HTML 中：

<html>
<body>
    <script>
        function JavaScripFunctionName1(arg1, arg2)
        {
            // something here
        }

        function JavaScripFunctionName2()
        {
            // something here
            return result;
        }        
    </script>
</body>
</html>

cefsharp执行javascript

2 个答案: