Wait for then() to finish - node.js

Question

I have been having a problem waiting for one part of my code to finish for me to run the other part,
How can part 1 finish before part 2?
var uidArray = [];
// Part 1
admin.auth().listUsers(1000).then(result => {
result.users.forEach(userRecord => {
uidArray.push(userRecord.uid);
console.log("pushing to uid array user " + userRecord.uid);
});
return;
}).catch(error => {
console.log("Error listing users:" + error);
});
uidArray.forEach(uid => {
// Part 2 of the code
});

Answer 1

You can use async-await for better data manipulation. However, forEach is by default asynchronous it can't wait until for each completes you can use below using async-await with try-catch block.
try{
var uidArray = [];
const result = await admin.auth().listUsers(1000);
for(const userRecord of result.users) {
uidArray.push(userRecord.uid);
console.log("pushing to uid array user " + userRecord.uid);
}
uidArray.forEach(uid => {
// Part 2 of the code
});
} catch(err) {
console.log(err);
}

Answer 2

var uidArray = [];
// Part 1
admin.auth().listUsers(1000).then(result => {
result.users.forEach(userRecord => {
uidArray.push(userRecord.uid);
console.log("pushing to uid array user " + userRecord.uid);
});
return;
}).catch(error => {
console.log("Error listing users:" + error);
}).then(()=>{
uidArray.forEach(uid => {
// Part 2 of the code
});
});
The key here is that after you start a promise, you can keep thening off it. Ideally you should also return a promise after each step, but it's not required.
This link has more information
https://javascript.info/promise-chaining

Answer 3

You can use below code using async-await as it is good for data manipulation.i prefer for loop instead using forEach.
async function test(){
try{
let result = await admin.auth().listUsers(1000);
let usersArray = result.users;
var uidArray = usersArray.map(function(item) { return item.uid; });
// here you can loop through uidArrar either for or forEach whatever you want
for(let i =0 ; i< uidArray.length; i++){
// your code to be executed in second part
}
} catch (e) {
//error
}
}
test()