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

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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 the .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).