Does javascript date have timezone?

I have a C# application that return in JSON an expiration date of an authentication token like this:

"expirationDate":"Fri, 27 Mar 2015 09:12:45 GMT"

In my TypeScript I check that the date is still valid here:

isAuthenticationExpired = [expirationDate: string]: boolean => {
    var now = new Date[].valueOf[];
    var exp: any = Date.parse[expirationDate].valueOf[];
    return exp - now