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

  • Article

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.

Note

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

Detect the ".NET CLR" User-Agent String

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).