通过C＃解析并执行JS

刘胜泫

2023-03-14

问题内容：

我有简单的搜寻器，可搜寻和搜寻页面。但是现在我有问题如何执行和解析该页面中的js链接。有谁知道如何解析和执行js页面吗？

例：

some_url易于使用webhtmltoolktit进行解析
JAVASCRIPT：runmeat（1,7,0,2,7,9）是js链接，它随后重定向到some_url2页面，然后我需要对该页面进行爬网。但是问题是如何在C＃中执行此javascript以获取some_url2链接？

问题答案：

为了回答标题为“如何在C＃中解析和执行JS”的问题，下面的代码包装了Windows脚本引擎。它支持32位和64位环境。

在您的特定情况下，这意味着取决于.JS代码，您可能必须模拟/实现一些HTMLDOM元素，例如“文档”，“窗口”等（使用MyItem类使用“命名项”功能）。正是Internet Explorer所做的）。

以下是您可以使用它的一些示例：

1）直接表达式求值：

Console.WriteLine(ScriptEngine.Eval("jscript", "1+2/3"));

将显示1.66666666666667

2）函数调用，带有可选参数：

using (ScriptEngine engine = new ScriptEngine("jscript"))
{
  ParsedScript parsed = engine.Parse("function MyFunc(x){return 1+2+x}");
  Console.WriteLine(parsed.CallMethod("MyFunc", 3));
}

将显示6

3）带有命名项和可选参数的函数调用：

using (ScriptEngine engine = new ScriptEngine("jscript"))
{
    ParsedScript parsed = engine.Parse("function MyFunc(x){return 1+2+x+My.Num}");
    MyItem item = new MyItem();
    item.Num = 4;
    engine.SetNamedItem("My", item);
    Console.WriteLine(parsed.CallMethod("MyFunc", 3));
}

[ComVisible(true)] // Script engines are COM components.
public class MyItem
{
    public int Num { get; set; }
}

将显示10。

编辑：我添加了使用CLSID代替脚本语言名称的可能性，因此我们可以重复使用新的快速IE9 +“chakra”
JavaScript引擎，如下所示：

using (ScriptEngine engine = new ScriptEngine("{16d51579-a30b-4c8b-a276-0ff4dc41e755}"))
{
    // continue with chakra now
}

这是完整的源代码：

/// <summary>
/// Represents a Windows Script Engine such as JScript, VBScript, etc.
/// </summary>
public sealed class ScriptEngine : IDisposable
{
    /// <summary>
    /// The name of the function used for simple evaluation.
    /// </summary>
    public const string MethodName = "EvalMethod";

    /// <summary>
    /// The default scripting language name.
    /// </summary>
    public const string DefaultLanguage = JavaScriptLanguage;

    /// <summary>
    /// The JavaScript or jscript scripting language name.
    /// </summary>
    public const string JavaScriptLanguage = "javascript";

    /// <summary>
    /// The javascript or jscript scripting language name.
    /// </summary>
    public const string VBScriptLanguage = "vbscript";

    /// <summary>
    /// The chakra javascript engine CLSID. The value is {16d51579-a30b-4c8b-a276-0ff4dc41e755}.
    /// </summary>
    public const string ChakraClsid = "{16d51579-a30b-4c8b-a276-0ff4dc41e755}";

    private IActiveScript _engine;
    private IActiveScriptParse32 _parse32;
    private IActiveScriptParse64 _parse64;
    internal ScriptSite Site;
    private Version _version;
    private string _name;

    [Guid("BB1A2AE1-A4F9-11cf-8F20-00805F2CD064"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IActiveScript
    {
        [PreserveSig]
        int SetScriptSite(IActiveScriptSite pass);
        [PreserveSig]
        int GetScriptSite(Guid riid, out IntPtr site);
        [PreserveSig]
        int SetScriptState(ScriptState state);
        [PreserveSig]
        int GetScriptState(out ScriptState scriptState);
        [PreserveSig]
        int Close();
        [PreserveSig]
        int AddNamedItem(string name, ScriptItem flags);
        [PreserveSig]
        int AddTypeLib(Guid typeLib, uint major, uint minor, uint flags);
        [PreserveSig]
        int GetScriptDispatch(string itemName, out IntPtr dispatch);
        [PreserveSig]
        int GetCurrentScriptThreadID(out uint thread);
        [PreserveSig]
        int GetScriptThreadID(uint win32ThreadId, out uint thread);
        [PreserveSig]
        int GetScriptThreadState(uint thread, out ScriptThreadState state);
        [PreserveSig]
        int InterruptScriptThread(uint thread, out System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo, uint flags);
        [PreserveSig]
        int Clone(out IActiveScript script);
    }

    [Guid("4954E0D0-FBC7-11D1-8410-006008C3FBFC"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IActiveScriptProperty
    {
        [PreserveSig]
        int GetProperty(int dwProperty, IntPtr pvarIndex, out object pvarValue);
        [PreserveSig]
        int SetProperty(int dwProperty, IntPtr pvarIndex, ref object pvarValue);
    }

    [Guid("DB01A1E3-A42B-11cf-8F20-00805F2CD064"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IActiveScriptSite
    {
        [PreserveSig]
        int GetLCID(out int lcid);
        [PreserveSig]
        int GetItemInfo(string name, ScriptInfo returnMask, out IntPtr item, IntPtr typeInfo);
        [PreserveSig]
        int GetDocVersionString(out string version);
        [PreserveSig]
        int OnScriptTerminate(object result, System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo);
        [PreserveSig]
        int OnStateChange(ScriptState scriptState);
        [PreserveSig]
        int OnScriptError(IActiveScriptError scriptError);
        [PreserveSig]
        int OnEnterScript();
        [PreserveSig]
        int OnLeaveScript();
    }

    [Guid("EAE1BA61-A4ED-11cf-8F20-00805F2CD064"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IActiveScriptError
    {
        [PreserveSig]
        int GetExceptionInfo(out System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo);
        [PreserveSig]
        int GetSourcePosition(out uint sourceContext, out int lineNumber, out int characterPosition);
        [PreserveSig]
        int GetSourceLineText(out string sourceLine);
    }

    [Guid("BB1A2AE2-A4F9-11cf-8F20-00805F2CD064"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IActiveScriptParse32
    {
        [PreserveSig]
        int InitNew();
        [PreserveSig]
        int AddScriptlet(string defaultName, string code, string itemName, string subItemName, string eventName, string delimiter, IntPtr sourceContextCookie, uint startingLineNumber, ScriptText flags, out string name, out System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo);
        [PreserveSig]
        int ParseScriptText(string code, string itemName, IntPtr context, string delimiter, int sourceContextCookie, uint startingLineNumber, ScriptText flags, out object result, out System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo);
    }

    [Guid("C7EF7658-E1EE-480E-97EA-D52CB4D76D17"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IActiveScriptParse64
    {
        [PreserveSig]
        int InitNew();
        [PreserveSig]
        int AddScriptlet(string defaultName, string code, string itemName, string subItemName, string eventName, string delimiter, IntPtr sourceContextCookie, uint startingLineNumber, ScriptText flags, out string name, out System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo);
        [PreserveSig]
        int ParseScriptText(string code, string itemName, IntPtr context, string delimiter, long sourceContextCookie, uint startingLineNumber, ScriptText flags, out object result, out System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo);
    }

    [Flags]
    private enum ScriptText
    {
        None = 0,
        //DelayExecution = 1,
        //IsVisible = 2,
        IsExpression = 32,
        IsPersistent = 64,
        //HostManageSource = 128
    }

    [Flags]
    private enum ScriptInfo
    {
        //None = 0,
        //IUnknown = 1,
        ITypeInfo = 2
    }

    [Flags]
    private enum ScriptItem
    {
        //None = 0,
        IsVisible = 2,
        IsSource = 4,
        //GlobalMembers = 8,
        //IsPersistent = 64,
        //CodeOnly = 512,
        //NoCode = 1024
    }

    private enum ScriptThreadState
    {
        //NotInScript = 0,
        //Running = 1
    }

    private enum ScriptState
    {
        Uninitialized = 0,
        Started = 1,
        Connected = 2,
        Disconnected = 3,
        Closed = 4,
        Initialized = 5
    }

    private const int TYPE_E_ELEMENTNOTFOUND = unchecked((int)(0x8002802B));
    private const int E_NOTIMPL = -2147467263;

    /// <summary>
    /// Determines if a script engine with the input name exists.
    /// </summary>
    /// <param name="language">The language.</param>
    /// <returns>true if the engine exists; false otherwise.</returns>
    public static Version GetVersion(string language)
    {
        if (language == null)
            throw new ArgumentNullException("language");

        Type engine;
        Guid clsid;
        if (Guid.TryParse(language, out clsid))
        {
            engine = Type.GetTypeFromCLSID(clsid, false);
        }
        else
        {
            engine = Type.GetTypeFromProgID(language, false);
        }
        if (engine == null)
            return null;

        IActiveScript scriptEngine = Activator.CreateInstance(engine) as IActiveScript;
        if (scriptEngine == null)
            return null;

        IActiveScriptProperty scriptProperty = scriptEngine as IActiveScriptProperty;
        if (scriptProperty == null)
            return new Version(1, 0, 0, 0);

        int major = GetProperty(scriptProperty, SCRIPTPROP_MAJORVERSION, 0);
        int minor = GetProperty(scriptProperty, SCRIPTPROP_MINORVERSION, 0);
        int revision = GetProperty(scriptProperty, SCRIPTPROP_BUILDNUMBER, 0);
        Version version = new Version(major, minor, Environment.OSVersion.Version.Build, revision);
        Marshal.ReleaseComObject(scriptProperty);
        Marshal.ReleaseComObject(scriptEngine);
        return version;
    }

    private static T GetProperty<T>(IActiveScriptProperty prop, int index, T defaultValue)
    {
        object value;
        if (prop.GetProperty(index, IntPtr.Zero, out value) != 0)
            return defaultValue;

        try
        {
            return (T)Convert.ChangeType(value, typeof(T));
        }
        catch
        {
            return defaultValue;
        }
    }

    /// <summary> 
    /// Initializes a new instance of the <see cref="ScriptEngine"/> class. 
    /// </summary> 
    /// <param name="language">The scripting language. Standard Windows Script engines names are 'jscript' or 'vbscript'.</param> 
    public ScriptEngine(string language)
    {
        if (language == null)
            throw new ArgumentNullException("language");

        Type engine;
        Guid clsid;
        if (Guid.TryParse(language, out clsid))
        {
            engine = Type.GetTypeFromCLSID(clsid, true);
        }
        else
        {
            engine = Type.GetTypeFromProgID(language, true);
        }
        _engine = Activator.CreateInstance(engine) as IActiveScript;
        if (_engine == null)
            throw new ArgumentException(language + " is not an Windows Script Engine", "language");

        Site = new ScriptSite();
        _engine.SetScriptSite(Site);

        // support 32-bit & 64-bit process 
        if (IntPtr.Size == 4)
        {
            _parse32 = (IActiveScriptParse32)_engine;
            _parse32.InitNew();
        }
        else
        {
            _parse64 = (IActiveScriptParse64)_engine;
            _parse64.InitNew();
        }
    }

    private const int SCRIPTPROP_NAME = 0x00000000;
    private const int SCRIPTPROP_MAJORVERSION = 0x00000001;
    private const int SCRIPTPROP_MINORVERSION = 0x00000002;
    private const int SCRIPTPROP_BUILDNUMBER = 0x00000003;

    /// <summary>
    /// Gets the engine version.
    /// </summary>
    /// <value>
    /// The version.
    /// </value>
    public Version Version
    {
        get
        {
            if (_version == null)
            {
                int major = GetProperty(SCRIPTPROP_MAJORVERSION, 0);
                int minor = GetProperty(SCRIPTPROP_MINORVERSION, 0);
                int revision = GetProperty(SCRIPTPROP_BUILDNUMBER, 0);
                _version = new Version(major, minor, Environment.OSVersion.Version.Build, revision);
            }
            return _version;
        }
    }

    /// <summary>
    /// Gets the engine name.
    /// </summary>
    /// <value>
    /// The name.
    /// </value>
    public string Name
    {
        get
        {
            if (_name == null)
            {
                _name = GetProperty(SCRIPTPROP_NAME, string.Empty);
            }
            return _name;
        }
    }

    /// <summary>
    /// Gets a script engine property.
    /// </summary>
    /// <typeparam name="T">The expected property type.</typeparam>
    /// <param name="index">The property index.</param>
    /// <param name="defaultValue">The default value if not found.</param>
    /// <returns>The value of the property or the default value.</returns>
    public T GetProperty<T>(int index, T defaultValue)
    {
        object value;
        if (!TryGetProperty(index, out value))
            return defaultValue;

        try
        {
            return (T)Convert.ChangeType(value, typeof(T));
        }
        catch
        {
            return defaultValue;
        }
    }

    /// <summary>
    /// Gets a script engine property.
    /// </summary>
    /// <param name="index">The property index.</param>
    /// <param name="value">The value.</param>
    /// <returns>true if the property was successfully got; false otherwise.</returns>
    public bool TryGetProperty(int index, out object value)
    {
        value = null;
        IActiveScriptProperty property = _engine as IActiveScriptProperty;
        if (property == null)
            return false;

        return property.GetProperty(index, IntPtr.Zero, out value) == 0;
    }

    /// <summary>
    /// Sets a script engine property.
    /// </summary>
    /// <param name="index">The property index.</param>
    /// <param name="value">The value.</param>
    /// <returns>true if the property was successfully set; false otherwise.</returns>
    public bool SetProperty(int index, object value)
    {
        IActiveScriptProperty property = _engine as IActiveScriptProperty;
        if (property == null)
            return false;

        return property.SetProperty(index, IntPtr.Zero, ref value) == 0;
    }

    /// <summary> 
    /// Adds the name of a root-level item to the scripting engine's name space. 
    /// </summary> 
    /// <param name="name">The name. May not be null.</param> 
    /// <param name="value">The value. It must be a ComVisible object.</param> 
    public void SetNamedItem(string name, object value)
    {
        if (name == null)
            throw new ArgumentNullException("name");

        _engine.AddNamedItem(name, ScriptItem.IsVisible | ScriptItem.IsSource);
        Site.NamedItems[name] = value;
    }

    internal class ScriptSite : IActiveScriptSite
    {
        internal ScriptException LastException;
        internal Dictionary<string, object> NamedItems = new Dictionary<string, object>();

        int IActiveScriptSite.GetLCID(out int lcid)
        {
            lcid = Thread.CurrentThread.CurrentCulture.LCID;
            return 0;
        }

        int IActiveScriptSite.GetItemInfo(string name, ScriptInfo returnMask, out IntPtr item, IntPtr typeInfo)
        {
            item = IntPtr.Zero;
            if ((returnMask & ScriptInfo.ITypeInfo) == ScriptInfo.ITypeInfo)
                return E_NOTIMPL;

            object value;
            if (!NamedItems.TryGetValue(name, out value))
                return TYPE_E_ELEMENTNOTFOUND;

            item = Marshal.GetIUnknownForObject(value);
            return 0;
        }

        int IActiveScriptSite.GetDocVersionString(out string version)
        {
            version = null;
            return 0;
        }

        int IActiveScriptSite.OnScriptTerminate(object result, System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo)
        {
            return 0;
        }

        int IActiveScriptSite.OnStateChange(ScriptState scriptState)
        {
            return 0;
        }

        int IActiveScriptSite.OnScriptError(IActiveScriptError scriptError)
        {
            string sourceLine = null;
            try
            {
                scriptError.GetSourceLineText(out sourceLine);
            }
            catch
            {
                // happens sometimes... 
            }
            uint sourceContext;
            int lineNumber;
            int characterPosition;
            scriptError.GetSourcePosition(out sourceContext, out lineNumber, out characterPosition);
            lineNumber++;
            characterPosition++;
            System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo;
            scriptError.GetExceptionInfo(out exceptionInfo);

            string message;
            if (!string.IsNullOrEmpty(sourceLine))
            {
                message = "Script exception: {1}. Error number {0} (0x{0:X8}): {2} at line {3}, column {4}. Source line: '{5}'.";
            }
            else
            {
                message = "Script exception: {1}. Error number {0} (0x{0:X8}): {2} at line {3}, column {4}.";
            }
            LastException = new ScriptException(string.Format(message, exceptionInfo.scode, exceptionInfo.bstrSource, exceptionInfo.bstrDescription, lineNumber, characterPosition, sourceLine));
            LastException.Column = characterPosition;
            LastException.Description = exceptionInfo.bstrDescription;
            LastException.Line = lineNumber;
            LastException.Number = exceptionInfo.scode;
            LastException.Text = sourceLine;
            return 0;
        }

        int IActiveScriptSite.OnEnterScript()
        {
            LastException = null;
            return 0;
        }

        int IActiveScriptSite.OnLeaveScript()
        {
            return 0;
        }
    }

    /// <summary> 
    /// Evaluates an expression using the specified language. 
    /// </summary> 
    /// <param name="language">The language.</param> 
    /// <param name="expression">The expression. May not be null.</param> 
    /// <returns>The result of the evaluation.</returns> 
    public static object Eval(string language, string expression)
    {
        return Eval(language, expression, null);
    }

    /// <summary> 
    /// Evaluates an expression using the specified language, with an optional array of named items. 
    /// </summary> 
    /// <param name="language">The language.</param> 
    /// <param name="expression">The expression. May not be null.</param> 
    /// <param name="namedItems">The named items array.</param> 
    /// <returns>The result of the evaluation.</returns> 
    public static object Eval(string language, string expression, params KeyValuePair<string, object>[] namedItems)
    {
        if (language == null)
            throw new ArgumentNullException("language");

        if (expression == null)
            throw new ArgumentNullException("expression");

        using (ScriptEngine engine = new ScriptEngine(language))
        {
            if (namedItems != null)
            {
                foreach (KeyValuePair<string, object> kvp in namedItems)
                {
                    engine.SetNamedItem(kvp.Key, kvp.Value);
                }
            }
            return engine.Eval(expression);
        }
    }

    /// <summary> 
    /// Evaluates an expression. 
    /// </summary> 
    /// <param name="expression">The expression. May not be null.</param> 
    /// <returns>The result of the evaluation.</returns> 
    public object Eval(string expression)
    {
        if (expression == null)
            throw new ArgumentNullException("expression");

        return Parse(expression, true);
    }

    /// <summary> 
    /// Parses the specified text and returns an object that can be used for evaluation. 
    /// </summary> 
    /// <param name="text">The text to parse.</param> 
    /// <returns>An instance of the ParsedScript class.</returns> 
    public ParsedScript Parse(string text)
    {
        if (text == null)
            throw new ArgumentNullException("text");

        return (ParsedScript)Parse(text, false);
    }

    private object Parse(string text, bool expression)
    {
        const string varName = "x___";
        object result;

        _engine.SetScriptState(ScriptState.Connected);

        ScriptText flags = ScriptText.None;
        if (expression)
        {
            flags |= ScriptText.IsExpression;
        }

        try
        {
            // immediate expression computation seems to work only for 64-bit 
            // so hack something for 32-bit... 
            System.Runtime.InteropServices.ComTypes.EXCEPINFO exceptionInfo;
            if (_parse32 != null)
            {
                if (expression)
                {
                    // should work for jscript & vbscript at least... 
                    text = varName + "=" + text;
                }
                _parse32.ParseScriptText(text, null, IntPtr.Zero, null, 0, 0, flags, out result, out exceptionInfo);
            }
            else
            {
                _parse64.ParseScriptText(text, null, IntPtr.Zero, null, 0, 0, flags, out result, out exceptionInfo);
            }
        }
        catch
        {
            if (Site.LastException != null)
                throw Site.LastException;

            throw;
        }

        IntPtr dispatch;
        if (expression)
        {
            // continue  our 32-bit hack... 
            if (_parse32 != null)
            {
                _engine.GetScriptDispatch(null, out dispatch);
                object dp = Marshal.GetObjectForIUnknown(dispatch);
                try
                {
                    return dp.GetType().InvokeMember(varName, BindingFlags.GetProperty, null, dp, null);
                }
                catch
                {
                    if (Site.LastException != null)
                        throw Site.LastException;

                    throw;
                }
            }
            return result;
        }

        _engine.GetScriptDispatch(null, out dispatch);
        ParsedScript parsed = new ParsedScript(this, dispatch);
        return parsed;
    }

    /// <summary>
    /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
    /// </summary>
    public void Dispose()
    {
        if (_parse32 != null)
        {
            Marshal.ReleaseComObject(_parse32);
            _parse32 = null;
        }

        if (_parse64 != null)
        {
            Marshal.ReleaseComObject(_parse64);
            _parse64 = null;
        }

        if (_engine != null)
        {
            Marshal.ReleaseComObject(_engine);
            _engine = null;
        }
    }
}

public sealed class ParsedScript : IDisposable
{
    private object _dispatch;
    private readonly ScriptEngine _engine;

    internal ParsedScript(ScriptEngine engine, IntPtr dispatch)
    {
        _engine = engine;
        _dispatch = Marshal.GetObjectForIUnknown(dispatch);
    }

    public object CallMethod(string methodName, params object[] arguments)
    {
        if (_dispatch == null)
            throw new InvalidOperationException();

        if (methodName == null)
            throw new ArgumentNullException("methodName");

        try
        {
            return _dispatch.GetType().InvokeMember(methodName, BindingFlags.InvokeMethod, null, _dispatch, arguments);
        }
        catch
        {
            if (_engine.Site.LastException != null)
                throw _engine.Site.LastException;

            throw;
        }
    }

    void IDisposable.Dispose()
    {
        if (_dispatch != null)
        {
            Marshal.ReleaseComObject(_dispatch);
            _dispatch = null;
        }
    }
}

[Serializable]
public class ScriptException : Exception
{
    public ScriptException()
        : base("Script Exception")
    {
    }

    public ScriptException(string message)
        : base(message)
    {
    }

    public ScriptException(Exception innerException)
        : base(null, innerException)
    {
    }

    public ScriptException(string message, Exception innerException)
        : base(message, innerException)
    {
    }

    protected ScriptException(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }

    public string Description { get; internal set; }
    public int Line { get; internal set; }
    public int Column { get; internal set; }
    public int Number { get; internal set; }
    public string Text { get; internal set; }
}

通过C＃解析并执行JS

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