JavaScript（Jscript）でIPアドレスを取得について

<html>
<body>
<form name="mainform">
<input type="text" name="ipaddress" value="">
</form>
<script language="JavaScript">
<!--
// 最初の処理時のみIPアドレスを取得する。(2回目以降はこのロジックは通らない)
if(document.mainForm.ipAddress.value == null
 || document.mainForm.ipAddress.value.length == 0){
	// ローカルIPアドレスを取得
	var wScriptShell = new ActiveXObject("WScript.Shell");
	var wshSysEnv = wScriptShell.Exec("ipconfig.exe");
	while ( !wshSysEnv.StdOut.AtEndOfStream ) {
		strLine = wshSysEnv.StdOut.ReadLine();
		iIP = strLine.indexOf("IP Address");
		if ( iIP >= 0 ) {
			iColon = strLine.indexOf( ":" );
			strAddress = strLine.substr( iColon + 2 );
			strAddress
			 = strAddress.substr( 0, strAddress.length - 1 );
			document.mainForm.ipAddress.value = strAddress;
		}
	}
}
// -->
</script>
</body>
</html>

inserted by FC2 system