I am trying to run a function asynchronously 20 times. I have the function definition:
import axios from 'axios';
async function updateUser (url, user) {
return new Promise((resolve, reject) => {
axios.put(url, JSON.stringify(user))
.then(response => {
//Folio returned code 204
console.log('The user has been updated');
resolve(response.data);
}).catch((err) => {
//Folio returned error
console.error(`Error Text: ${err.response.data}`);
console.error(`Error Code: ${err}`);
});
});
};
export {updateUser};
Then I am trying to loop through users in an external JSON, and update them to my system 20 at a time:
import {updateUser} from './updateUser.js';
import usersjson from './jsons/users.json';
let promises=[];
if (usersjson.users.length) {
try {
for (const user of usersjson.users) {
update = new promise ((resolve,reject) => {
updateUser(url, user)
.then((list) => {resolve(list)})
.catch((error)=>{reject(error)})
});
promises.push(update);
if (promises.length = 20) {
await Promise.all(promises)
.then((responses)=> {
console.log(responses);
promises=[];
}).catch((err)=> {
console.log(err);
});
}
}
} catch(err)=> {
console.log(err);
}
}
However, I am getting an error message in the console:
await Promise.all(promises)
^^^^^
SyntaxError: Unexpected reserved word
My node version is 12.19.0 (based on previous questions, it seems it has to be at least 10, so that shouldn't be the issue).
When I run the function without await, they work correctly (i.e. the users are updated on my system). It also seems that the for loop is asynchronous by itself, but I'm afraid that if there will be too many calls simultaneously my system will block the API, so I want to make 20-50 calls at a time, tops.
In order to use await you need to declare the function in which you are putting the await as async
For example:
const functionReturningPromise = (input) => {
return new Promise((resolve, reject) => {
if (!input) {
return reject();
}
return resolve();
});
}
const functionAwaitingPromise = async () => {
for (let i = 0; i < 20; i +=1) {
try {
await functionReturningPromise(i);
console.log(i);
} catch (error) {
console.log(error);
}
}
}