I have been studying promises, await and async functions. While I was just in the stage of learning promises, I realized that the following: When I would send out two requests, there was no guarantee that they would come in the order that they are written in the code. Of course, with routing and packets of a network. When I ran the code below, the requests would resolve in no specific order.
const getCountry = async country => {
await fetch(`https://restcountries.com/v2/name/${country}`)
.then(res => res.json())
.then(data => {
console.log(data[0]);
})
.catch(err => err.message);
};
getCountry('portugal');
getCountry('ecuador');
At this point, I hadn't learned about async and await. So, the following code works the exact way I want it. Each request, waits until the other one is done.
Is this the most simple way to do it? Are there any redundancies that I could remove? I don't need a ton of alternate examples; unless I am doing something wrong.
await fetch(`https://restcountries.com/v2/name/${country}`)
.then(res => res.json())
.then(data => {
console.log(data[0]);
})
.catch(err => err.message);
};
const getCountryData = async function () {
await getCountry('portugal');
await getCountry('ecuador');
};
getCountryData();
Thanks in advance,
Yes, that's the correct way to do so. Do realize though that you're blocking each request so they run one at a time, causing inefficiency. As I mentioned, the beauty of JavaScript is its asynchronism, so take advantage of it. You can run all the requests almost concurrently, causing your requests to speed up drastically. Take this example:
// get results...
const getCountry = async country => {
const res = await fetch(`https://restcountries.com/v2/name/${country}`);
const json = res.json();
return json;
};
const getCountryData = async countries => {
const proms = countries.map(getCountry); // create an array of promises
const res = await Promise.all(proms); // wait for all promises to complete
// get the first value from the returned array
return res.map(r => r[0]);
};
// demo:
getCountryData(['portugal', 'ecuador']).then(console.log);
// it orders by the countries you ordered
getCountryData(['ecuador', 'portugal']).then(console.log);
// get lots of countries with speed
getCountryData(['mexico', 'china', 'france', 'germany', 'ecaudor']).then(console.log);Edit: I just realized that Promise.all auto-orders the promises for you, so no need to add an extra sort function. Here's the sort fn anyways for reference if you take a different appoach:
myArr.sort((a, b) =>
(countries.indexOf(a.name.toLowerCase()) > countries.indexOf(b.name.toLowerCase())) ? 1 :
(countries.indexOf(a.name.toLowerCase()) < countries.indexOf(b.name.toLowerCase()))) ? -1 :
0
);
I tried it the way @deceze recommended and it works fine: I removed all of the .then and replaced them with await. A lot cleaner this way. Now I can use normal try and catch blocks.
// GET COUNTRIES IN ORDER
const getCountry = async country => {
try {
const status = await fetch(`https://restcountries.com/v2/name/${country}`);
const data = await status.json();
renderCountry(data[0]); // Data is here. Now Render HTML
} catch (err) {
console.log(err.name, err.message);
}
};
const getCountryData = async function () {
await getCountry('portugal');
await getCountry('Ecuador');
};
btn.addEventListener('click', function () {
getCountryData();
});
Thank you all.