---
title: "How to: Detect Whether the .NET Framework 3.5 Is Installed"
ms.date: "03/30/2017"
helpviewer_keywords: 
  - "verifying whether.NET Framework 3.5 is installed [WPF]"
  - "detecting .NET Framework 3.5 installation [WPF]"
  - "detecting whether.NET Framework 3.5 is installed [WPF]"
  - "determining whether.NET Framework 3.5 is installed [WPF]"
ms.assetid: 8556a9d2-1eb8-48ef-919c-5baf22a2a9a2
---
# How to: Detect Whether the .NET Framework 3.5 Is Installed
Before administrators can deploy Windows Presentation Foundation (WPF) applications on a system that targets the .NET Framework 3.5, they must first confirm that the .NET Framework 3.5 runtime is present. This topic provides a script written in HTML/JavaScript that administrators can use to determine whether the .NET Framework 3.5 is present on a system.  
  
> [!NOTE]
> For more detailed information on installing, deploying, and detecting the .NET Framework, see [Install the .NET Framework for developers](/dotnet/framework/install/guide-for-developers).  
  
## Example  
 When the .NET Framework 3.5 is installed, the MSI adds ".NET CLR" and the version number to the UserAgent string. The following example shows a script embedded in a simple HTML page. The script searches the UserAgent string to determine whether the .NET Framework 3.5 is installed, and displays a status message on the results of the search.  
  
> [!NOTE]
> This script is designed for Internet Explorer. Other browsers may not include .NET CLR information in the UserAgent string.  
  
```html  
<HTML>  
  <HEAD>  
    <TITLE>Test for the .NET Framework 3.5</TITLE>  
    <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8" />  
    <SCRIPT LANGUAGE="JavaScript">  
    <!--  
    var dotNETRuntimeVersion = "3.5.0.0";  
  
    function window::onload()  
    {  
      if (HasRuntimeVersion(dotNETRuntimeVersion))  
      {  
        result.innerText =   
          "This machine has the correct version of the .NET Framework 3.5."  
      }   
      else  
      {  
        result.innerText =   
          "This machine does not have the correct version of the .NET Framework 3.5." +  
          " The required version is v" + dotNETRuntimeVersion + ".";  
      }  
      result.innerText += "\n\nThis machine's userAgent string is: " +   
        navigator.userAgent + ".";  
    }  
  
    //  
    // Retrieve the version from the user agent string and   
    // compare with the specified version.  
    //  
    function HasRuntimeVersion(versionToCheck)  
    {  
      var userAgentString =   
        navigator.userAgent.match(/.NET CLR [0-9.]+/g);  
  
      if (userAgentString != null)  
      {  
        var i;  
  
        for (i = 0; i < userAgentString.length; ++i)  
        {  
          if (CompareVersions(GetVersion(versionToCheck),   
            GetVersion(userAgentString[i])) <= 0)  
            return true;  
        }  
      }  
  
      return false;  
    }  
  
    //  
    // Extract the numeric part of the version string.  
    //  
    function GetVersion(versionString)  
    {  
      var numericString =   
        versionString.match(/([0-9]+)\.([0-9]+)\.([0-9]+)/i);  
      return numericString.slice(1);  
    }  
  
    //  
    // Compare the 2 version strings by converting them to numeric format.  
    //  
    function CompareVersions(version1, version2)  
    {  
      for (i = 0; i < version1.length; ++i)  
      {  
        var number1 = new Number(version1[i]);  
        var number2 = new Number(version2[i]);  
  
        if (number1 < number2)  
          return -1;  
  
        if (number1 > number2)  
          return 1;  
      }  
  
      return 0;  
    }  
  
    -->  
    </SCRIPT>  
  </HEAD>  
  
  <BODY>  
    <div id="result" />  
  </BODY>  
</HTML>  
```  
  
 If the search for the ".NET CLR " version is successful, the following type of status message appears:  
  
 `This machine has the correct version of the .NET Framework 3.5.`  
  
 `This machine's userAgent string is: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; InfoPath.2; .NET CLR 3.0.590; .NET CLR 3.5.20726; MS-RTC LM 8).`  
  
 Otherwise, the following type of status message appears:  
  
 `This machine does not have the correct version of the .NET Framework 3.5. The required version is v3.5.0.0.`  
  
 `This machine's userAgent string is: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; InfoPath.2; .NET CLR 3.0.590; MS-RTC LM 8).`  
  
## See also

- [Detect Whether the .NET Framework 3.0 Is Installed](how-to-detect-whether-the-net-framework-3-0-is-installed.md)
