How to: Detect Whether the .NET Framework 3.0 Is Installed

Before administrators can deploy Microsoft .NET Framework applications on a system, they must first confirm that the .NET Framework runtime is present. This topic provides a script written in HTML/JavaScript that administrators can use to determine whether .NET Framework is present on a system.

NoteNote:

For more detailed information on installing, deploying, and detecting the Microsoft .NET Framework, see the discussion in Deploying Microsoft .NET Framework Version 3.0.

When .NET Framework 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 .NET Framework is installed, and displays a status message on the results of the search.

<HTML>
  <HEAD>
    <TITLE>Test for the .NET Framework 3.0</TITLE>
    <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8" />
    <SCRIPT LANGUAGE="JavaScript">
    <!--
    var dotNETRuntimeVersion = "3.0.04425.00";
    
    function window::onload()
    {
      if (HasRuntimeVersion(dotNETRuntimeVersion))
      {
        result.innerText = 
          "This machine has the correct version of the .NET Framework 3.0: " 
          + dotNETRuntimeVersion
      } 
      else
      {
        result.innerText = 
          "This machine does not have the correct version of the .NET Framework 3.0."
      }
      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 3.0: 3.0.04425.00

This machine's userAgent string is: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; InfoPath.1; .NET CLR 2.0.50727; .NET CLR 3.0.04425.00).

Otherwise, the following type of status message appears:

This machine does not have correct version of the .NET Framework 3.0.

This machine's userAgent string is: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; InfoPath.1; .NET CLR 2.0.50727).

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