how to send response in hhtp module - node.js

Question

I'm new to node.js, So how to send duration in response in http module i tried sending it through req.write and req.writeHead(), but its not working.Help me with this issue
var https = require('https');
const config_KEYS = require('./config.js');
exports.handler = (event, context, callback) => {
var userLat = event.userLat;
var userLong = event.userLong;
var destinationLat = event.destinationLat;
var destinationLong = event.destinationLong;
var params = {
host:'maps.googleapis.com',
path: '/maps/api/distancematrix/json?units=imperial&origins='+userLat+","+userLong+'&destinations='+destinationLat+","+destinationLong+'&key='+config_KEYS.GOOGLE_API_KEY+'&departure_time=now'
};
var req = https.request(params, function(res) {
let data = '';
console.log('STATUS: ' + res.statusCode);
// res.setEncoding('utf8');
res.on('data', function(chunk) {
data += chunk;
});
res.on('end', function() {
console.log("DONE");
const parsedData = JSON.parse(data);
console.log("data ===>>>>",parsedData);
var duration = parsedData.rows[0].elements[0].duration_in_traffic.text;
var obj = {}
obj.duration = duration
res.end(duration) ;
});
});
req.write(callback)
req.end();
};

Answer 1

In node js https there is one method like res.end() to send data after https request ends
Example:
const https = require('https');
const fs = require('fs');
const options = {
pfx: fs.readFileSync('test/fixtures/test_cert.pfx'),
passphrase: 'sample'
};
https.createServer(options, (req, res) => {
res.writeHead(200);
res.end('hello world\n');
}).listen(8000);
Here what you want to achieve is use function in res.on('end', ) and then return to that function. So, In your case it will not send in res.on('end', ) because untimately you're returning a value to function not a method.
Here is the solution:
const parsedData = JSON.parse(data);
console.log("data ===>>>>",parsedData);
var duration = parsedData.rows[0].elements[0].duration_in_traffic.text;
req.end('duration');
one more way is you can use callback. For the reference I am providing one link
Callback https