Promise.all()

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Promise.all(iterable) 方法會回傳一個 promise 物件,此 promise 物件會於 iterable 參數中的所有 promise 都 resolved 時轉為 resolved 狀態,或是在其中的任一個 promise 變 reject 傳入失敗訊息時轉成 rejected 狀態。

語法

Promise.all(iterable);
iterable
An iterable object, such as an  Array. See iterable.

回傳值

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

描述

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

If any of the passed in promises rejects, the all Promise immediately rejects with the value of the promise that rejected, discarding all the other promises whether or not they have resolved. If an empty array is passed, then this method resolves immediately.

範例

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 rejected if one of the elements is rejected and Promise.all fails fast: If you have four promises which resolve after a timeout, and one rejects immediately, then Promise.all rejects 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"

// Evenly, it's possible to use .catch
Promise.all([p1, p2, p3, p4, p5]).then(values => { 
  console.log(values);
}).catch(reason => { 
  console.log(reason)
});

//From console: 
//"reject"

規範

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 2017 Draft (ECMA-262)
The definition of 'Promise.all' in that specification.
Draft  

覽瀏器相容性

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

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