var WSHShell = WScript.CreateObject("WScript.Shell");
var fso, f;
fso = new ActiveXObject("Scripting.FileSystemObject");
f = fso.CreateTextFile("gmt.txt", true);

var d, tz, s = "";
d = new Date();
tz = d.getTimezoneOffset();
if (tz < 0)
s += "+" + tz / 60;
else if (tz == 0)
s += "0";
else
s += "-" + tz / 60;

f.WriteLine(s);
f.Close();