How to use .then for async functions

Question

So I am trying to chain request from an api and I am aware of that this is an asynchronous request. However it is my understanding that using .then() returns a promise, and that the code waits for it to be resolved before moving on to the next .then() . When I console.log the variable encryptedAccountId instead of returning it, I get the desired result. But when I try to put that into the next url, it says the variable is undefined. I have also trying using await and async but to no luck. What am I missing here?

let summonerName = 'nightblue3';
const region = ['na1', 'br1', 'eun1', 'euw1', 'jp1', 'kr', 'la1', 'la2', 'oc1', 'ru', 'tr1'];
let endIndex = 100;
let beginIndex = 0;
const fetch = require("node-fetch");

  let userUrl = `https://${region[0]}.api.riotgames.com/lol/summoner/v4/summoners/by-name/${summonerName}?api_key=${apiKey}`
  fetch(userUrl).then(res => {
        return res.json()})
        .then(getEncryptedAcccountId=> {
        var encryptedAccountId = (getEncryptedAcccountId.accountId)
        return encryptedAccountId})
        .then(fetch(`https://${region[0]}.api.riotgames.com/lol/match/v4/matchlists/by-account/${encryptedAccountId}?endIndex=${endIndex}&beginIndex=${beginIndex}&api_key=${apiKey}`))```

Answer 1

You could write it easier:

fetch(userUrl).then(res => res.json())
   .then(({ accountId }) => fetch(`your_url_with_${accountId}`))

Answer 2

The function you pass to then() will, indeed, not be called until the promise then is called on resolves.

 .then(fetch(`https://${region[...

The problem is that you are not passing a function to then . You are immediately calling fetch() and passing its return value (which is a promise, not a function).

Pass a function instead:

.then((encryptedAccountId) => fetch(`https://${region[...

---

You might also like to move to async / await syntax which is generally more readable:

(async function () {
  let summonerName = "nightblue3";
  const region = ['na1', 'br1', 'eun1', 'euw1', 'jp1', 'kr', 'la1', 'la2', 'oc1', 'ru', 'tr1'];
  let endIndex = 100;
  let beginIndex = 0;
  const fetch = require("node-fetch");

  let userUrl = `https://${region[0]}.api.riotgames.com/lol/summoner/v4/summoners/by-name/${summonerName}?api_key=${apiKey}`;
  const userResponse = await fetch(userUrl);
  const userData = await userResponse.json();
  const encryptedAccountId = userData.accountId;
  const matchlists = await fetch(
    `https://${region[0]}.api.riotgames.com/lol/match/v4/matchlists/by-account/${encryptedAccountId}?endIndex=${endIndex}&beginIndex=${beginIndex}&api_key=${apiKey}`
  );
  // ...
})();