The Promise.all() method returns a single Promise that resolves when all of the promises in the iterable argument have resolved, or rejects with the reason of the first promise that rejects.

Syntax

Promise.all(iterable);
iterable
An iterable object (such as an Array) of promises.

Return value

A Promise that resolves when all of the promises in the given iterable have resolved, or rejects if any of the promises rejects.

Description

This method can be useful for aggregating the results of multiple promises.

Fulfillment:
If all of the passed-in promises fulfill, Promise.all is fulfilled with an array of the values from the passed-in promises, in the same order as defined in the iterable.
If an empty array is passed, then this method resolves immediately.

Rejection:
If any of the passed-in promises reject, Promise.all immediately rejects with the value of the promise that rejected, whether or not the other promises have resolved.

Examples

Using Promise.all

Promise.all waits for all fulfillments (or the first rejection).

var p1 = Promise.resolve(3);
var p2 = 1337;
var p3 = new Promise((resolve, reject) => {
  setTimeout(resolve, 100, 'foo');
}); 

Promise.all([p1, p2, p3]).then(values => { 
  console.log(values); // [3, 1337, "foo"] 
});

Promise.all fail-fast behaviour

Promise.all is immediately rejected if any of the elements are rejected. For example, if you pass in four promises that resolve after a timeout and one promise that rejects immediately, then Promise.all will reject immediately.

var p1 = new Promise((resolve, reject) => { 
  setTimeout(resolve, 1000, 'one'); 
}); 
var p2 = new Promise((resolve, reject) => { 
  setTimeout(resolve, 2000, 'two'); 
});
var p3 = new Promise((resolve, reject) => {
  setTimeout(resolve, 3000, 'three');
});
var p4 = new Promise((resolve, reject) => {
  setTimeout(resolve, 4000, 'four');
});
var p5 = new Promise((resolve, reject) => {
  reject('reject');
});

Promise.all([p1, p2, p3, p4, p5]).then(values => { 
  console.log(values);
}, reason => {
  console.log(reason)
});

//From console:
//"reject"

//You can also use .catch
Promise.all([p1, p2, p3, p4, p5]).then(values => { 
  console.log(values);
}).catch(reason => { 
  console.log(reason)
});

//From console: 
//"reject"

Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Promise.all' in that specification.
Standard Initial definition in an ECMA standard.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Promise.all' in that specification.
Draft  

Browser compatibility

Feature Chrome Edge Firefox Internet Explorer Opera Safari Servo
Basic Support32.0(Yes)29.0No support197.1No support
Feature Android Chrome for Android Edge Mobile Firefox for Android IE Mobile Opera Mobile Safari Mobile
Basic Support4.4.432.0(Yes)29No support(Yes)8.0

See also

Document Tags and Contributors

 Last updated by: jackblackevo,