I'm trying to create a "synchronized like loop" with async await but I get the strange behavior of getting all the results after the first promise instead.
here is my test case. See how you get all together instead of print 1 by 1
const p = () => new Promise((resolve) =>{
setTimeout(()=>{
resolve(Math.floor(Date.now() / 1000))
},1000)
})
const test = () =>{
[1,2,3,4,5,6,7,8,9,10].map(async () =>{
const e = await p();
console.log(e)
});
}
test();Like I mention in comments, map is not Promise aware. There are alternatives like Bluebirds.map,.. But the easy option is to use a for loop,..
Keeping to your example were your wanting to loop an array, you can use the for of variant too. Changing to for (let a = 1; a <= 10; a ++) will work too.
eg.
const p = () => new Promise((resolve) =>{
setTimeout(()=>{
resolve(Math.floor(Date.now() / 1000))
},1000)
})
const test = async () =>{
for (const a of [1,2,3,4,5,6,7,8,9,10]) {
const e = await p();
console.log(e)
}
}
test();It's also worth pointing out bluebirds map has another trick up it's sleeve, it has a concurrency option. This is very handy to prevent thrashing that can happen with Promise.all, you basically say you want to do x promises at a time, eg. you have 10 promises to do, but you find it's more optimal to do 3 concurrently.
aync / awaitBut if you used say bluebird promise, it does have a promise based map. Alternatively in your example a for-loop would work.