Best way to wait for .forEach() to complete
The quickest way to make this work using ES6 would be just to use a for..of
loop.
const myAsyncLoopFunction = async (array) => {
const allAsyncResults = []
for (const item of array) {
const asyncResult = await asyncFunction(item)
allAsyncResults.push(asyncResult)
}
return allAsyncResults
}
Or you could loop over all these async requests in parallel using Promise.all()
like this:
const myAsyncLoopFunction = async (array) => {
const promises = array.map(asyncFunction)
await Promise.all(promises)
console.log(`All async tasks complete!`)
}
var foo = [1,2,3,4,5,6,7,8,9,10];
If you're actually doing async stuff inside the loop, you can wrap it in a promise ...
var bar = new Promise((resolve, reject) => {
foo.forEach((value, index, array) => {
console.log(value);
if (index === array.length -1) resolve();
});
});
bar.then(() => {
console.log('All done!');
});
If there is no asynchronous code inside the forEach
, forEach
is not asynchronous, for example in this code:
array.forEach(function(item){
//iterate on something
});
alert("Foreach DONE !");
you will see the alert after forEach
finished.
Otherwise (You have something asynchronous inside), you can wrap the forEach
loop in a Promise:
var bar = new Promise((resolve, reject) => {
foo.forEach((value, index, array) => {
console.log(value);
if (index === array.length -1) resolve();
});
});
bar.then(() => {
console.log('All done!');
});
Credit: @rolando-benjamin-vaz-ferreira