如何在 WebBrowser 控件中使用 XPath？答案

【问题标题】：How to using XPath in WebBrowser Control?如何在 WebBrowser 控件中使用 XPath？
【发布时间】：2015-03-16 12:59:42
【问题描述】：

在 C# WinForms 示例应用程序中，我使用了 WebBrowser 控件。我想使用 JavaScript XPath 来选择单个节点。为此，我使用XPathJS

但是使用下面的代码，vResult的返回值总是NULL。

        bool completed = false;
        WebBrowser wb = new WebBrowser();
        wb.ScriptErrorsSuppressed = true;
        wb.DocumentCompleted += delegate { completed = true; };
        wb.Navigate("http://stackoverflow.com/");

        while (!completed)
        {
            Application.DoEvents();
            Thread.Sleep(100);
        }

        if (wb.Document != null)
        {
            HtmlElement head = wb.Document.GetElementsByTagName("head")[0];
            HtmlElement scriptEl = wb.Document.CreateElement("script");
            mshtml.IHTMLScriptElement element = (mshtml.IHTMLScriptElement)scriptEl.DomElement;
            element.src = "https://raw.github.com/andrejpavlovic/xpathjs/master/build/xpathjs.min.js";
            head.AppendChild(scriptEl);

            // Initialize XPathJS
            wb.Document.InvokeScript("XPathJS.bindDomLevel3XPath");

            string xPathQuery = @"count(//script)";
            string code = string.Format("document.evaluate('{0}', document, null, XPathResult.ANY_TYPE, null);", xPathQuery);
            var vResult = wb.Document.InvokeScript("eval", new object[] { code });
        }

有没有办法用 WebBrowser 控件来做 JavaScript XPath？

Rem：我想避免使用 HTML Agility Pack，我想直接操作 WebBrowser 控件的 DOM 内容 mshtml.IHTMLElement

【问题讨论】：

标签： javascript c# xpath webbrowser-control evaluate

【解决方案1】：

我找到了解决办法，代码如下：

    bool completed = false;
    WebBrowser wb = new WebBrowser();
    wb.ScriptErrorsSuppressed = true;
    wb.DocumentCompleted += delegate { completed = true; };
    wb.Navigate("http://stackoverflow.com/");

    while (!completed)
    {
        Application.DoEvents();
        Thread.Sleep(100);
    }

    if (wb.Document != null)
    {
            HtmlElement head = wb.Document.GetElementsByTagName("head")[0];
            HtmlElement scriptEl = wb.Document.CreateElement("script");
            mshtml.IHTMLScriptElement element = (mshtml.IHTMLScriptElement)scriptEl.DomElement;
            element.text = System.IO.File.ReadAllText(@"wgxpath.install.js");
            head.AppendChild(scriptEl);

            // Call wgxpath.install() from JavaScript code, which will ensure document.evaluate
            wb.Document.InvokeScript("eval", new object[] { "wgxpath.install()" });

            string xPathQuery = @"count(//script)";
            string code = string.Format("document.evaluate('{0}', document, null, XPathResult.NUMBER_TYPE, null).numberValue;", xPathQuery);
            int iResult = (int) wb.Document.InvokeScript("eval", new object[] { code });
    }

我使用“纯 JavaScript XPath 库”：wicked-good-xpath 并下载 wgxpath.install.js

【讨论】：