Angular sync http call with underscore?

This is my code:

$scope.updatePosts = function() {
  Posts.getIdsFromServer('http://localhost/postIds')
  .then(function(ids) {
    _.each(ids, function(id) {
      Posts.getByIdFromDb(id)
      .then(function(p) {
        if(p) {
          if(p.enabled) {
            Posts.getFromServer('http://localhost/post/' + id)
            .then(function(post) {
              Posts.update(post);
            })
          }
        } else {
          Posts.getFromServer('http://localhost/post/' + id)
          .then(function(post) {
            Posts.insert(post);
          })
        }
      });
    });
  }, function(error) {
    console.log(error);
  })
};

This code breaks because of _.each

I searched SO and found this:

function processCoolStuff(coolStuffs) {
  return $q.all(_.map(coolStuffs, makeStuffCooler));
}
processCoolStuff(…).then(showAllMyCoolStuff);

But I cannot make it work, becasue I have too many async functions.

And I can get like 10000 posts and 10000 http calls, if I can use above method, will it consume a lot of memory?

How to solve it?