Node JS Async.parallel - node.js

Question

I'm learning node and would like to optimize the code I did. I tried using Async.parallel to perform the operations and when finished return a json.
I am new to js node and I'm trying to do with async.parallel but I returned [Function] in other code that I'm trying to understand it
getTabletIntRout: function(req, res) {
var reqMAC = req.param('id_tablet');
Tablet.findOne(reqMAC).populate('rout_tablet').exec(function(err, tablet) {
if (err) return next(err);
if (!tablet) return next();
var arrRoutes = tablet.rout_tablet;
if (arrRoutes.length > 0) {
var routesNotRemoved = [];
arrRoutes.forEach(function(route) {
if (route.removed == 'no') {
Rout.findOne(route.id)
.populate('rout_assigned') // Pin
.populate('in_rout') // Tablet
.populate('rout_description_assigned')
.exec(function(err, rout2) {
var arrRout = rout2.rout_assigned;
var routsNotRemoved = [];
if (arrRout.length > 0) {
arrRout.forEach(function(ruta) {
if (ruta.removed == 'no') {
routsNotRemoved.push(ruta);
}
});
}
var arrTablets = rout2.in_rout;
var tabletsNotRemoved = [];
if (arrTablets.length > 0) {
arrTablets.forEach(function(tab) {
if (tab.removed == 'no') {
tabletsNotRemoved.push(tab);
}
});
}
var arrDesc = rout2.rout_description_assigned;
var descripNotRemoved = [];
if (arrDesc.length > 0) {
arrDesc.forEach(function(desc) {
if (desc.removed == 'no') {
descripNotRemoved.push(desc);
}
});
}
rout2.rout_assigned = routsNotRemoved;
rout2.in_rout = tabletsNotRemoved;
rout2.rout_description_assigned = descripNotRemoved;
routesNotRemoved.push(rout2);
});
}
});
setTimeout(function() {
if (routesNotRemoved.length > 0) {
res.json({ info: routesNotRemoved });
} else {
return res.json({"error": "-1", "message": "Todas las rutas asociadas a esa tablet están eliminadas"});
}
}, 2000);
} else {
return res.json({"error": "-2", "message": "No existen rutas asociadas en esa tablet"});
}
}););});}},

Answer 1

I will try to provide some thoughts, hopefully some will make sense in your domain.
Extract a function to make people understand what you're doing in that big function
So instead of
Tablet.findOne(reqMAC).populate('rout_tablet').exec(function(err, tablet) { // ...
You would have
Tablet.findOne(reqMAC).populate('rout_tablet').exec(meaningfulFunctionName);
Don't repeat yourself
So your code becomes shorter and whenever the reader of your code finds a function name he / she already knows what is happening inside that
if (arrRout.length > 0) {
arrRout.forEach(function(ruta) {
if (ruta.removed == 'no') {
routsNotRemoved.push(ruta);
}
});
}
No need to check for empty arrRout as the argument function to arrRout.forEach will simply not run in the case of length being zero.
What you wrote is just a filter function, so why not using filter? Like so
arrRout.filter(function(ruta) {
return ruta.removed == 'no';
});
You can also reuse this, if you extract the anonymous function, for arrTablets and arrDesc.
On the argument: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
Don't use a huge if else
Either check for the inverse or return a default or something that makes sense in your domain, but don't have that big chunk of logic, it makes it hard to reason about your code.
Extract more function so that it's easier to use async
You might want to have something like this
async.waterfall([
function(next) {
// here you can put
// Tablet.findOne(reqMAC).populate('rout_tablet').exec
// invoke next with err, tablet
},
function(tablet, next) {
async.each(arrRoutes, function(arrRoute, nextEach) {
// write your code logic here
});
}
], function() {
// decide what to invoke res.json with
});
Remember to extract functions after you're done putting the logic inside the async steps, I didn't do it so it is more clear where to put what.
I hope this makes sense, feel free to ask if you have any doubts.
Next time you post a question please make sure to properly indent it, don't just paste it here.