c# - 在 WebBrowser 中调用一个脚本，并等待它完成运行(同步)

Question

我正在使用 webBrowser.Document.InvokeScript("Function") 来运行 javascript，它位于使用 Winforms WebBrowser 打开的本地文件中。

问题是，我需要 javascript 在继续之前完成执行。我该如何等待/收听？

这是我的 C# 代码:

    private void Button1_ItemClick_1(object sender, DevExpress.XtraBars.ItemClickEventArgs e)
    {
        webBrowser.Document.InvokeScript("Script_A");
        Method_A();
        DialogResult = System.Windows.Forms.DialogResult.OK;
    }

Javascript 代码:

<script>function Script_A() { Script_B(); }</script>

如何确保在 Script_B 完成之前不执行 Method_A？

Answer 1

使用 async/await，您可以等待脚本执行而不会阻塞 UI。

public async void AMethod()
{
    string script =
     @"<script>
        function Script_A() { 
            Script_B(); 
            window.external.Completed(); //call C#: CallbackObject's Completed method
        }
        function Script_B(){
            alert('in script');
        }
    </script>";

    TaskCompletionSource<bool> tcs = new TaskCompletionSource<bool>();

    webBrowser1.ObjectForScripting = new CallbackObject(tcs);
    //Ensure DocumentText is loaded before invoking "InvokeScript",
    //by extension method "SetDocumentTextAsync" (below)
    await webBrowser1.SetDocumentTextAsync(script);
    webBrowser1.Document.InvokeScript("Script_A");

    await tcs.Task;

    MessageBox.Show("Script executed");
}


[ComVisible(true)]
public class CallbackObject
{
    TaskCompletionSource<bool> _tcs = null;

    public CallbackObject(TaskCompletionSource<bool> tcs)
    {
        _tcs = tcs;
    }
    public void Completed()
    {
        _tcs.TrySetResult(true);
    }
}

public static class BrowserExtensions
{
    public static Task SetDocumentTextAsync(this WebBrowser wb, string html)
    {
        TaskCompletionSource<object> tcs = new TaskCompletionSource<object>();
        WebBrowserDocumentCompletedEventHandler completedEvent = null;
        completedEvent = (sender, e) =>
        {
            wb.DocumentCompleted -= completedEvent;
            tcs.SetResult(null);
        };
        wb.DocumentCompleted += completedEvent;

        wb.ScriptErrorsSuppressed = true;
        wb.DocumentText = html;

        return tcs.Task;
    }
}