Parallel: How to pass parameter into task function?

I need to pass variable to parallel tasks. How do I do that? I’m trying to escape a callback hell and have them nicely organized in a file. How would I make this

async.parallel({
                profile_data: function(callback) {
                    console.log('running getUserInfo');
                    api.get_user_info({
                        uToken: token
                    }, function(response) {
                        if (response['data']) {
                            callback(null, response['data']);
                            return;
                        }
                        callback('not profile', response);
                    });
                },
                notification_data: function(callback) {
                    console.log('running getUserNot');
                    api.get_user_notification_summary({
                        uToken: token
                    }, function(response) {
                        if (response['data']) {
                            callback(null, response['data']);
                            return;
                        }
                        callback('not notifications', response);
                    });
                }
            }, function(err, results) {
                if (err !== null) {
                    console.log(err, results);
                } else {
                    res.locals.session = results['profile_data'];
                    res.locals.session.notification = results['notification_data'];
                }               
                next();
            });

to this

var getProfileData = function(token, cb){
  ...
  cb();
}

var getNotificationData = function(token, cb){
  ...
  cb();
}

async.parallel({
   profile_data: getProfileData,
   notification_data: getNotificationData
}, function(err, result){
   console.log(result['profile_data'], result['notification_data']);
});

I don’t know how to pass token into each task…

[jlfaber]

async.parallel({ profile_data: getProfileData.bind(null, token), notification_data: getNotificationData.bind(null, token) }, function (err, result) { console.log(result.profile_data, result.notification_data); });

[LiamGoodacre]

For those interested, the following are roughly equivalent:

f(a, b, c, d)

async.apply(f, a, b)(c, d)

var part = async.apply(f, a, b)
part(c, d)

f.bind(null, a, b)(c, d)

var part = f.bind(null, a, b)
part(c, d)

f.apply(null, [a, b, c, d])

f.call(null, a, b, c, d)

(I expanded the multiple calls of async.apply and f.bind just in case it wasn’t obvious.)

You can find more information about the specifics of these here:

• async.apply
• Function.prototype.bind
• Function.prototype.apply
• Function.prototype.call