AngularJS:旧 Angular 版本中的 $q.race() [英] AngularJS: $q.race() in old angular versions

问题描述

Angular 1.5.8 实现了一个 $q.race() 方法，该方法接受一个 promise 数组并返回一个 promise，该 promise 使用第一个已解析的 promise 的值进行解析.

Angular 1.5.8 implements a $q.race() method which takes an array of promises and returns a promise which is resolves with the value of the first resolved promise.

但是我现在坚持使用 angular 1.4，需要某种功能，例如 $q.any 或 $q.race 方法.

However i am stuck with angular 1.4 for now and need some kind of functionality like a $q.any or $q.race method.

目前我在 .then() 中使用标志来记住"明显不理想的承诺状态.

Currently I use flags inside .then() to "remember" the state of promises which obviously is not ideal.

var resolvedPromise = null;

promise1.then(function(data){
  if(!resolvedPromise === 'promise2'){
    resolvedPromise = 'promise1';
    successcallback(data)
  }
})

promise2.then(function(data){
  if(!resolvedPromise === 'promise1'){
    resolvedPromise = 'promise2';
    successcallback(data)
  }
})

问题

我只需要一次为两个承诺工作:

I only need this to work for two promises at a time:

myRaceFkt(p1,p2)
  .then(successcallback)

是否有更优雅的解决方案，而无需访问 1.5.8 改进的 $q-api?

Is there a more elegant solution without having access to the improved $q-api of 1.5.8?

推荐答案

function myRaceFn(promises){
   return $q(function(resolve, reject) { 
     promises.forEach(function(promise) {
       promise.then(resolve, reject);
     });
   });
}
myRaceFn([promise1, promise2]).then(....

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