How do I run a function after using array.map? - node.js

Question

What I'm trying to do is run a function after using array.map. Theoretically, I should be able to just run the after the array.map. However, for some reason, it's running the function before array.map is finished. How do I fix this?
Here's my code.
var channelIds = channelNames.map(function (name) {
request(`https://www.googleapis.com/youtube/v3/channels?key=${key}&forUsername=${name}&part=id`, function (error, response, body) {
if (error) {
callback(error);
} else {
var data = JSON.parse(body);
if (data.items.length == 0) {
callback(`Error: No channel id found for ${name}`);
} else {
return data.items[0].id;
}
}
});
});
function test() {
console.log(channelIds);
}
test();
EDIT:
One way which was suggested was to use async.map. For some reason, it doesn't want to run the specified callback function like how the documentation says it should.
Here's how I'm doing it now.
async.map(channelNames, function (name) {
request(`https://www.googleapis.com/youtube/v3/channels?key=${key}&forUsername=${name}&part=id`, function (error, response, body) {
if (error) {
callback(error);
} else {
var data = JSON.parse(body);
if (data.items.length == 0) {
callback(`Error: No channel id found for ${name}`);
} else {
return data.items[0].id;
}
}
});
}, function (error, results) {
console.log(results);
});
Documentation: https://caolan.github.io/async/docs.html#map

Answer 1

How about using Promise.all to resolve all async functions before you call test method?
Try this :
const promiseArray = channelNames.map(function (name) {
return new Promise(function (resolve, reject) {
request(`https://www.googleapis.com/youtube/v3/channels?key=${key}&forUsername=${name}&part=id`, function (error, response, body) {
if (error) {
callback(error); return reject(error);
} else {
var data = JSON.parse(body);
if (data.items.length == 0) {
callback(`Error: No channel id found for ${name}`);
return reject(`Error: No channel id found for ${name}`);
} else {
return resolve(data.items[0].id);
}
}
});
});
});
Promise.all(promiseArray).then(function(channelIds) {
console.log(channelIds);
})