passport.use(new CitiStrategy({
        appID: {APPID},
        name:{默认为wechat,可以设置组件的名字}
        appSecret: {APPSECRET},
        client:{wechat|web},
        callbackURL: {CALLBACKURL},
        scope: {snsapi_userinfo|snsapi_base},
        state:{STATE},
        getToken: {getToken},
        saveToken: {saveToken}
      },
      function(accessToken, refreshToken, profile,expires_in, done) {
        return done(err,profile);
      }
));

The `callbackURL`, `scope` and `state` can be overwritten in `passport.authenticate` middleware.

The `getToken` and `saveToken` can be provided to initialize Wechat OAuth instance.

router.get("/auth/citi", passport.authenticate("citi", options));

router.get(
  "/auth/citi/callback",
  passport.authenticate("citi", {
    failureRedirect: "/auth/fail",
    successReturnToOrRedirect: "/"
  })
);