TypeScript: readFile function in io.ts

gistfile1

readFile: function(path) {
    try {
        var file = fso.OpenTextFile(path);
        var bomChar = !file.AtEndOfStream ? file.Read(2) : '';
        var str = bomChar;
        if ((bomChar.charCodeAt(0) == 0xFE && bomChar.charCodeAt(1) == 0xFF)
            || (bomChar.charCodeAt(0) == 0xFF && bomChar.charCodeAt(1) == 0xFE)) {
            // Reopen the file as unicode
            file.close();
            file = fso.OpenTextFile(path, 1 /* IOMode.ForReading */, false /* Create */, -1 /* Format.TristateUseUnicode */);

            str = '';
            // ReadAll will helpfully throw an error if this is a 0-byte file
            if (!file.AtEndOfStream) {
                str = file.ReadAll();
            }
            file.close();
        }
        else if (bomChar.charCodeAt(0) == 0xEF && bomChar.charCodeAt(1) == 0xBB) {
            // Reopen the file as utf-8
            file.Close();
            var stream = new ActiveXObject("ADODB.Stream");
            stream.Mode = 3; /* adModeReadWrite = 3*/
            stream.Type = 2; /* adTypeText = 2 */
            stream.CharSet = "utf-8";

            stream.Open();
            stream.LoadFromFile(path);
            str = '';
            if (!stream.EOS) {
                str = stream.ReadText();
            }
            stream.Close();
        }
        else {
            if (!file.AtEndOfStream) {
                str += file.ReadAll();
            }
            file.close();
        }

        return <string>str;
    }
    catch (err) {
        throw new Error("Error reading file \"" + path + "\": " + err.message);
    }
}