Creating a server-side script to fetch from - node.js

Question

I want to fetch countries and cities from my front end, but I know first, I need to make a server-side script on the backend to be able to do so.
If geography is a mock package where I can do so, and this is the code I have thus far, how could I prepare my backend to receive these fetch requests?
app.get('/:locations', function (req, res) {
Geography.init().then(function() {
console.log(Geography)
Geography.open(req.params.url).then(function(site) {
console.log(Geography)
site.analyze().then(function(results) {
res.json(results)
})
})
})
})
Would it look something like this? (incomplete, of course....)
select
countries
cities

Answer 1

Taking the library I used as an example in the comments:
In the example provided in the readme, a JSON reponse is returned of an array of cities matching the filter (or close to it) such as [{}, {}, {}, ...]
So, if you wanted to form a response from this, you could just take some of the data. For example, if you wanted to return the country along with a latitude and longitude you could do:
// let "cities" be the JSON response from the library
// cities[0] is the first object in the array from the response
res.json({
"country": cities[0].country,
"location": {
"lat": cities[0].loc[1], //longitude comes first
"lon": cities[0].loc[0]
}
});
You could implement this with your GET endpoint like:
app.get('/:locations', function (req, res) {
cities = citiesLibrary.filter(city => city.name.match(req.params.locations));
});
But if you wanted to return all the results returned by the library then you could simply just use:
res.json(cities);