Promise
🏷️ Javascript
Promise for a value that will be available later
Promise.then(resolved).catch(rejected);.then can also handle rejection as its second argument
Promise.then(resolved, rejected);.then(null, rejected) === .catch(rejected)
.then and .catch return a new promise
If there is an error in .then, it will be caught in catch
Create promise
new Promise((resolve) => resolve()) / Promise.resolve();
new Promise((resolve, reject) => reject()) / Promise.reject();Promise exists in *three/ states:
- Pending
- Settled:
- Fullfilled
- Rejection
After a promise is settled, all reactions are evaluated
Promise.all
Run promises concurrently
If a promise is rejected, Promise.all will be rejected
Promise.race
The first settled promise win