How to make a function synchronous in nodejs - node.js

Question

I made this function that retrieve the flight data from Aviationstack API(a flight API ). I'm new to nodejs and I want to make this function synchronous using 'sync-request' so that when I call anywhere I could get something in return. here is the function code :
function get_flights_by_date(date) {
let url = 'http://api.aviationstack.com/v1/flights?access_key=xxxxxxxxxxxxxxxxx&flight_status=scheduled'
request(url, function (err, response, body) {
if (err) {
console.log('error:', error);
} else {
let vol = JSON.parse(body)
num = vol.pagination.limit
for (let i = 0; i < num; i++) {
dep = vol.data[i].departure.airport
depart = vol.data[i].departure.timezone
arrival = vol.data[i].arrival.timezone
arr = vol.data[i].arrival.airport
flight_date = vol.data[i].flight_date
number = vol.data[i].flight.number
console.log('flight number:' + ' ' + number + ' ' + 'from' + ' ' + depart + ' ' + 'at' + ' ' + dep + ' ' + 'airport' + ' ' + 'to' + ' ' + arrival + ' ' + 'at' + ' ' + arr + ' ' + 'airport' + ' ' + 'on' + ' ' + flight_date + '.')
}
}
});
}

Answer 1

This is not a way to make a sync code in node js
There are few approach to make any code sync
callback
What you are doing, this will fail when you will call directly from other function. instead you can do this
function get_flights_by_date(date, callback) {
let url = 'http://api.aviationstack.com/v1/flights?access_key=xxxxxxxxxxxxxxxxx&flight_status=scheduled'
request(url, function (err, response, body) {
if (err) {
console.log('error:', error);
callback(err);
} else {
let vol = JSON.parse(body)
num = vol.pagination.limit
for (let i = 0; i < num; i++) {
dep = vol.data[i].departure.airport
depart = vol.data[i].departure.timezone
arrival = vol.data[i].arrival.timezone
arr = vol.data[i].arrival.airport
flight_date = vol.data[i].flight_date
number = vol.data[i].flight.number
console.log('flight number:' + ' ' + number + ' ' + 'from' + ' ' + depart + ' ' + 'at' + ' ' + dep + ' ' + 'airport' + ' ' + 'to' + ' ' + arrival + ' ' + 'at' + ' ' + arr + ' ' + 'airport' + ' ' + 'on' + ' ' + flight_date + '.')
}
callback(null, number)
}
});}
function mainFunction(){
var date = '';
get_flights_by_date(date, function(err, result){
if(err){
return err
}
return result
})
}
promise
function get_flights_by_date(date) {
return new Promise(function (resolve, reject) {
let url =
"http://api.aviationstack.com/v1/flights?access_key=xxxxxxxxxxxxxxxxx&flight_status=scheduled";
request(url, function (err, response, body) {
if (err) {
console.log("error:", error);
reject(err);
} else {
let vol = JSON.parse(body);
num = vol.pagination.limit;
for (let i = 0; i < num; i++) {
dep = vol.data[i].departure.airport;
depart = vol.data[i].departure.timezone;
arrival = vol.data[i].arrival.timezone;
arr = vol.data[i].arrival.airport;
flight_date = vol.data[i].flight_date;
number = vol.data[i].flight.number;
}
resolve(number);
}
});});
}
async function main() {
try {
await get_flights_by_date("");
} catch (error) {}
}
Async lib
or you can use this lib to do your entire code here https://medium.com/velotio-perspectives/understanding-node-js-async-flows-parallel-serial-waterfall-and-queues-6f9c4badbc17
I would recommend you to go for async lib as it is easy to scale in this fashion

Answer 2

I would totally avoid using synchronous code when ever possible, as this does not scale. This is a very bad practice, and will halt your server as long as the request is still fetching...
You can (And should) use async/await, or Promise to wait for the data while making sure your server is available.
If you want to avoid the then callback on Promise, just use async/await
Converted to use Promise and async/await:
function get_flights_by_date(date) {
const url = 'http://api.aviationstack.com/v1/flights?access_key=xxxxxxxxxxxxxxxxx&flight_status=scheduled'
return new Promise((resolve, reject) => {
request(url, (err, response, body) => {
if (err) {
reject(err);
} else {
const data = JSON.parse(body); // Process your data
resolve(data);
}
});
})
}
function promiseExample() {
get_flights_by_date(new Date()).then(resultData => console.log(resultData))
}
async function example() {
const resultData = await get_flights_by_date(new Date());
console.log(resultData);
}