javascript - Angular : How do I execute an array of defered in order?

Question

我有一组异步函数，只有在前一个函数已被解析时才运行一个异步函数才有意义。您可以将它们视为 HTT 获取对不同 URL 的请求，例如

$http.get('/step1')
$http.get('/step2')
$http.get('/step3')
$http.get('/step4')

如何序列化它们？

编辑:数组中有 N 个。所以我不能明确地展开它们并用“then”加入它们，例如:

var calls = Array()

for(var i = 0; i < N; i++)
{
    var d = $q.defer();

    ...

    calls.push(d.promise);
}

..

// How to do resolve the elements of 'calls' in order?

编辑 2:

我愿意:

Running Step #0 
Step completed: #0 OK 
Running Step #1 
Step completed: #1 OK 
Running Step #2 
Step completed: #2 OK 
Running Step #3 
Step completed: #3 OK 
Running Step #4 
Step completed: #4 OK 
Running Step #5 
Step completed: #5 OK 

不是

Running Step #0 
Running Step #1 
Running Step #2 
Running Step #3 
Running Step #4 
Running Step #5 
Step completed: #0 OK 
Step completed: #1 OK 
Step completed: #2 OK 
Step completed: #3 OK 
Step completed: #4 OK 
Step completed: #5 OK 

Answer 1

为简洁起见，使用 lodash。

_.reduce(_.rest(calls), function(promise, call) {
  return promise.then(function() {
    return call();
  });
}, _.first(calls)()).then(function() {
  // do something after they are all done sequentially.
});