您可以使用asyncmodule，它对您一一提出请求非常有帮助。下面是来自 async 官方文档的示例代码，理解起来相当直观。

  function asyncForEach (arr, iterator, callback) {
    queue = arr.slice(0)
        // create a recursive iterator
    function next (err) {
      if (err) return callback(err)

            // if the queue is empty, call the callback with no error
      if (queue.length === 0) return callback(null)

            // call the callback with our task
            // we pass `next` here so the task can let us know when to move on to the next task
      iterator(queue.shift(), next)
    }

        // start the loop;
    next()
  }

function sampleAsync (param, done) {
// put a callback when function is done its work 
}

  asyncForEach(result, function (param, done) { // result is the array you pass as iterator
    sampleAsync(param, function (message) {
      console.log(message)
      done()
    })
  }, function () {
    console.log('callback')
    callback(SOME_RESULT)
  })

}

我过去解决这个问题的方法之一是使用间隔计时器，有点像这样：

var isSending = false;
var sendMessages = setInterval(function() {
  if(!isSending) {
    isSending = true;
    sendTextMessage(block.pop().text, sender, function(){
      if(block.length) {
       isSending = false;
      } else {
        clearInterval(sendMessages);
        //Done
      }
    })
  }
})

function sendTextMessage(text, sender, callback) {
    let messageData = { text:text}
    request({
        url: 'https://graph.facebook.com/v2.6/me/messages',
        qs: {access_token:token},
        method: 'POST',
        json: {
            recipient: {id:sender},
            message: messageData,
        }
    }, function(error, response, body) {
        if (response.statusCode >= 200 &&  response.statusCode < 300){
            if(callback) callback('success')
        }
    })
}

我最终遵循了@Matt Diamond 的建议并执行了如下所示的递归函数：

function buildFlow(block, sender){
    var i = 0;
    recursive()
    /*  for(var x in block){
        sendTextMessage(block[x], block[x].type, sender)
        console.log(x)
    }*/
    function recursive(){
        if (i<Object.keys(block).length){
            sendTextMessage(block[Object.keys(block)[i]], block[Object.keys(block)[i]].type, sender, function(){
                i++
                recursive()
            })

        }else{
            i = 0
        }
    }
}

感谢所有提供帮助的人，不胜感激。