Use this tag for questions about features finalized in ECMAScript 2017. Do *not* use this tag if the code in question merely *uses* one of the features, *unless* the feature is cause of the problem.
Proposals finalized in 2017 include:
Questions tagged [ecmascript-2017]
387 questions
4
votes
4 answers
How can I remove an event listener no matter how the callback is defined
For years I ran into problems trying to remove an event listener in JavaScript. Often I would have to create an independent function as the handler. But that is just sloppy and, especially with the addition of arrow functions, just a pain.
I am not…
Intervalia
- 10,248
- 2
- 30
- 60
4
votes
2 answers
how to reuse es6 class in vue js?
How to reuse some existing ES6 classes in Vue Js.
Have a class which has a variable being updated by observable.
class A {
public a: string;
someobservable.subscribe((a) =>{
this.a = a;
})
}
In vue.JS have created the object…
SHUBHAM RAGHUWANSHI
- 43
- 1
- 6
4
votes
1 answer
JavaScript async/await not awaiting properly?
I'm having an issue with JavaScript's async/await functions. This is happening on an internal application that I can't share the source for, but I put together a quick generic reproduction of my issue:
function sleep(ms) {
return new…
CaptObvious
- 83
- 1
- 1
- 7
4
votes
1 answer
javascript: async / await – propagation required the entire call chain up?
I am wrapping a function returning a promises into an async function on a small helper function...
trash(filesArray, {
glob: false
})
.then(() => {
resolve(true);
}).catch((err) => {
return err;
})
…because I like to use it synchronous…
Frank N
- 9,625
- 4
- 80
- 110
4
votes
3 answers
Convert async await in while loop to promises
I can't figure out how to convert async await functionality in a while loop to a promise based implementation.
repl showing the async await version
https://repl.it/repls/IdealisticPepperyCoding
var dependency = false;
function checkDependency()…
Zack Lucky
- 671
- 3
- 10
- 25
4
votes
1 answer
Calling super class' async method from async method in extending class
I'm writing JavaScript (> ECMAScript 6) and I can't figure how to call a super class' async method in an extending class' method.
This is what I'm trying to do:
class SuperClass {
constructor(){}
async method() {
return;
…
zniwalla
- 367
- 4
- 17
4
votes
1 answer
Using Promises with Await/Async Correctly
I'm having some issues understanding how the Promise functionality works, I have previously used Bluebird but I wanted to try to learn the new await/async standard in order to improve as a programmer. I have used async/await and created promises…
Crafty
- 41
- 2
4
votes
2 answers
Converting await in infinite for loop into raw promise.then
As far as I know, async/await is just syntactic sugar over promise.then. Consider this code snippet:
function sleep(n){
return new Promise(res => setTimeout(res, n));
}
function* range(n){
var i = 0;
while(i < n) yield i++;
}
async…
Derek 朕會功夫
- 92,235
- 44
- 185
- 247
4
votes
1 answer
how to properly use the async and await keywords within a map
I have the following snippet of code
export const fetchPosts = () => async dispatch => {
const res = await axios.get(`${url}/posts`, { headers: { ...headers } });
console.log(res.data);
let posts = res.data.map(p => (p.comments =…
Strahinja Ajvaz
- 2,521
- 5
- 23
- 38
4
votes
2 answers
How does `for..of` loop resolve the iterator from an object?
For an object to implement iterable interface it must implement [Symbol.iterator] key that points to a function that returns the iterator. I'm wondering if the for..of loop internally calls this method on an object to get that iterator?
The reason…
Max Koretskyi
- 101,079
- 60
- 333
- 488
4
votes
0 answers
Implement PassportJS (local-strategy) custom callback using async/await
I've implemented passport local strategy using async/await as below
const strategy = new LocalStrategy(
async(username, password, done) => {
try {
// Find the user given the username
const user = await User.findOne({ username });
…
Jajati
- 77
- 7
4
votes
2 answers
ES8 using arrow function with async and await
I'm currently learning how to use ES8's fetch, async and await I currently have this code that works:
const url = "https://api.icndb.com/jokes/random";
async function tellJoke() {
let data = await (await fetch(url)).json();
return…
ricardoNava
- 685
- 1
- 7
- 26
4
votes
3 answers
How do you create a named async arrow function?
Currently, I have this code:
async function getConnection(){
// logic here...
}
To make it consistent with the rest of my codebase, I want to change it to an arrow function. I've tried async getConnection () => { ... } but that didn't seem to…
ifvictr
- 141
- 2
- 3
- 13
4
votes
2 answers
Why does .catch() not catch reject() within Promise constructor within loop at an async function unless Error is passed?
Given
(async () => {
const p = await new Promise((resolve, reject) => setTimeout(() => {
reject(new Error(1))
}, Math.floor(Math.random() * 1000))); return p})()
.then(data => console.log(data))
.catch(err =>…
guest271314
- 1
- 15
- 104
- 177
4
votes
1 answer
jQuery proxy doesn't call async functions
I've found that I can't call async functions with $.proxy. My case was that I proxied event listeners so that they'd still have the same context, but as soon as I tried proxying to an async function, it just didn't get called - also, no errors were…
macbem
- 1,180
- 2
- 9
- 21