How to inject Javascript in WebBrowser control

Question

I ve tried this   string newScript   textBox1 Text  HtmlElement head   browserCtrl Document GetElementsByTagName  head   0   HtmlElement scriptEl   browserCtrl Document CreateElement  script    lblStatus Text   scriptEl GetType   ToString    scriptEl SetAttribute  type    text javascript    head AppendChild scriptEl   scriptEl InnerHtml    function sayHello     alert  hello         scriptEl InnerHtml and scriptEl InnerText both give errors   System NotSupportedException  Property is not supported on this type of HtmlElement     at System Windows Forms HtmlElement set InnerHtml String value     at SForceApp Form1 button1 Click Object sender  EventArgs e  in d  jsight installs SForceApp SForceApp Form1 cs line 31    at System Windows Forms Control OnClick EventArgs e     at System Windows Forms Button OnClick EventArgs e     at System Windows Forms Button OnMouseUp MouseEventArgs mevent     at System Windows Forms Control WmMouseUp Message amp  m  MouseButtons button  Int32 clicks     at System Windows Forms Control WndProc Message amp  m     at System Windows Forms ButtonBase WndProc Message amp  m     at System Windows Forms Button WndProc Message amp  m     at System Windows Forms Control ControlNativeWindow OnMessage Message amp  m     at System Windows Forms Control ControlNativeWindow WndProc Message amp  m     at System Windows Forms NativeWindow Callback IntPtr hWnd  Int32 msg  IntPtr wparam  IntPtr lparam    Is there an easy way to inject a script into the dom

User · Answer

this is a solution using mshtml  IHTMLDocument2 doc   new HTMLDocumentClass    doc write new object     File ReadAllText filePath      doc close     IHTMLElement head    IHTMLElement   IHTMLElementCollection doc all tags  head    item null  0   IHTMLScriptElement scriptObject    IHTMLScriptElement doc createElement  script    scriptObject type     text javascript   scriptObject text     function btn1 OnClick str       alert  you clicked    str         HTMLHeadElementClass head  appendChild  IHTMLDOMNode scriptObject

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Here is a VB Net example if you are trying to retrieve the value of a variable from within a page loaded in a WebBrowser control   Step 1  Add a COM reference in your project to Microsoft HTML Object Library  Step 2  Next  add this VB Net code to your Form1 to import the mshtml library          Imports mshtml  Step 3  Add this VB Net code above your  Public Class Form1  line           lt System Runtime InteropServices ComVisibleAttribute True  gt   Step 4  Add a WebBrowser control to your project  Step 5  Add this VB Net code to your Form1 Load function          WebBrowser1 ObjectForScripting   Me  Step 6  Add this VB Net sub which will inject a function  CallbackGetVar  into the web page s Javascript     Public Sub InjectCallbackGetVar ByRef wb As WebBrowser      Dim head As HtmlElement     Dim script As HtmlElement     Dim domElement As IHTMLScriptElement      head   wb Document GetElementsByTagName  head   0      script   wb Document CreateElement  script       domElement   script DomElement     domElement type    text javascript      domElement text    function CallbackGetVar myVar    window external Callback GetVar eval myVar           head AppendChild script  End Sub   Step 7  Add the following VB Net sub which the Javascript will then look for when invoked   Public Sub Callback GetVar ByVal vVar As String      Debug Print vVar  End Sub   Step 8  Finally  to invoke the Javascript callback  add this VB Net code when a button is pressed  or wherever you like   Private Sub Button1 Click ByVal sender As System Object  ByVal e As System EventArgs  Handles Button1 Click     WebBrowser1 Document InvokeScript  CallbackGetVar   New Object     NameOfVarToRetrieve    End Sub   Step 9  If it surprises you that this works  you may want to read up on the Javascript  eval  function  used in Step 6  which is what makes this possible   It will take a string and determine whether a variable exists with that name and  if so  returns the value of that variable

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Here is the easiest way that I found after working on this   string javascript    alert  Hello         or any combination of your JavaScript commands     including function calls  variables    etc      WebBrowser webBrowser1 is what you are using for your web browser webBrowser1 Document InvokeScript  eval   new object     javascript       What global JavaScript function eval str  does is parses and executes whatever is written in str  Check w3schools ref here

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The managed wrapper for the HTML document doesn t completely implement the functionality you need  so you need to dip into the MSHTML API to accomplish what you want   1  Add a reference to MSHTML  which will probalby be called  Microsoft HTML Object Library  under COM references   2  Add  using mshtml   to your namespaces   3  Get a reference to your script element s IHTMLElement   IHTMLElement iScriptEl    IHTMLElement scriptEl DomElement    4  Call the insertAdjacentText method  with the first parameter value of  afterBegin    All the possible values are listed here   iScriptEl insertAdjacentText  afterBegin    function sayHello     alert  hello          5  Now you ll be able to see the code in the scriptEl InnerText property   Hth  Richard

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For some reason Richard s solution didn t work on my end  insertAdjacentText failed with an exception   This however seems to work   HtmlElement head   webBrowser1 Document GetElementsByTagName  head   0   HtmlElement scriptEl   webBrowser1 Document CreateElement  script    IHTMLScriptElement element    IHTMLScriptElement scriptEl DomElement  element text    function sayHello     alert  hello       head AppendChild scriptEl   webBrowser1 Document InvokeScript  sayHello      This answer explains how to get the IHTMLScriptElement interface into your project

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I used this  D  HtmlElement script   this WebNavegador Document CreateElement  SCRIPT    script SetAttribute  TEXT    function GetNameFromBrowser          return  My name is David              this WebNavegador Document Body AppendChild script     Then you can execute and get the result with   string myNameIs    string this WebNavegador Document InvokeScript  GetNameFromBrowser      I hope to be helpful

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If all you really want is to run javascript  this would be easiest  VB  Net    MyWebBrowser Navigate  javascript function foo   alert  hello    foo        I guess that this wouldn t  inject  it but it ll run your function  if that s what you re after    Just in case you ve over-complicated the problem    And if you can figure out how to inject in javascript  put that into the body of the function  foo  and let the javascript do the injection for you

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As a follow-up to the accepted answer  this is a minimal definition of the IHTMLScriptElement interface which does not require to include additional type libraries    ComImport  ComVisible true   Guid   3050f28b-98b5-11cf-bb82-00aa00bdce0b     InterfaceTypeAttribute ComInterfaceType InterfaceIsIDispatch    TypeLibType TypeLibTypeFlags FDispatchable   public interface IHTMLScriptElement        DispId 1006       string text   set   return  MarshalAs UnmanagedType BStr   get        So a full code inside a WebBrowser control derived class would look like   protected override void OnDocumentCompleted      WebBrowserDocumentCompletedEventArgs e        base OnDocumentCompleted e           Disable text selection      var doc   Document      if  doc    null                var heads   doc GetElementsByTagName   head            if  heads Count  gt  0                        var scriptEl   doc CreateElement   script                if  scriptEl    null                                var element    IHTMLScriptElement scriptEl DomElement                  element text                         function disableSelection                                                  document body onselectstart function    return false                              document body ondragstart function     return false                                             heads 0  AppendChild scriptEl                   doc InvokeScript   disableSelection

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You can always use a  DocumentStream  or  DocumentText  property  For working with HTML documents I recommend a HTML Agility Pack

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What you want to do is use Page RegisterStartupScript key  script      See here for more details  http   msdn microsoft com en-us library aa478975 aspx  What you basically do is build your javascript string  pass it to that method and give it a unique id  in case you try to register it twice on a page    EDIT  This is what you call trigger happy  Feel free to down it

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HtmlDocument doc   browser Document  HtmlElement head   doc GetElementsByTagName  head   0   HtmlElement s   doc CreateElement  script    s SetAttribute  text   function sayHello     alert  hello         head AppendChild s   browser Document InvokeScript  sayHello       tested in  NET 4   Windows Forms App   Edit  Fixed case issue in function set

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i use this   webBrowser Document InvokeScript  execScript   new object      alert 123     JavaScript

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If you need to inject a whole file then you can use this   With Browser Document    Dim Head As HtmlElement    GetElementsByTagName  head   0     Dim Script As HtmlElement    CreateElement  script      Dim Streamer As New StreamReader  lt Here goes path to file as String gt      Using Streamer        Script SetAttribute  text   Streamer ReadToEnd       End Using    Head AppendChild Script      InvokeScript  lt Here goes a method name as String and without parentheses gt   End With   Remember to import System IO in order to use the StreamReader  I hope this helps

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I believe the most simple method to inject Javascript in a WebBrowser Control HTML Document from c  is to invoke the   execScript  method with the code to be injected as argument   In this example the javascript code is injected and executed at global scope   var jsCode  alert  hello world from injected code      WebBrowser Document InvokeScript  execScript   new Object     jsCode   JavaScript        If you want to delay execution  inject functions and call them after   var jsCode  function greet msg  alert msg       WebBrowser Document InvokeScript  execScript   new Object     jsCode   JavaScript                      WebBrowser Document InvokeScript  greet  new object     hello world       This is valid for Windows Forms and WPF WebBrowser controls   This solution is not cross browser because  execScript  is defined only in IE and Chrome  But the question is about Microsoft WebBrowser controls and IE is the only one supported   For a valid cross browser method to inject javascript code  create a Function object with the new Keyword  This example creates an anonymous function with injected code and executes it  javascript implements closures and the function has access to global space without local variable pollution    var jsCode  alert  hello world       new Function code        Of course  you can delay execution   var jsCode  alert  hello world      var inserted new Function code                     inserted      Hope it helps

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Also  in  NET 4 this is even easier if you use the dynamic keyword   dynamic document   this browser Document  dynamic head   document GetElementsByTagName  head   0   dynamic scriptEl   document CreateElement  script    scriptEl text        head AppendChild scriptEl

[c#] How to inject Javascript in WebBrowser control?

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