意外回调执行顺序答案

【问题标题】：unexpected callback execution order意外回调执行顺序
【发布时间】：2016-03-05 16:48:33
【问题描述】：

我正在编写一个 hubot 脚本来按区域列出我在 AWS 中的所有 CloudFormation 堆栈。我已经写了以下内容，它可以工作，除了数据输出的顺序。脚本是：

key = process.env.HUBOT_AWS_ACCESS_KEY_ID
secret = process.env.HUBOT_AWS_SECRET_ACCESS_KEY
defaultRegions = 'us-east-1,us-west-2,eu-west-1'

_ = require 'underscore'
moment = require 'moment'
AWS = require 'aws-sdk'

getRegionStacks = (region, logger, msg) ->
    msg.send "In region #{region}:"
    AWS.config.region = region
    cloudFormation = new AWS.CloudFormation()
    params = {
        StackStatusFilter: [ 'CREATE_COMPLETE' ]
    }
    cloudFormation.listStacks params, (err, data) ->
        if err
            logger.error "Received error #{JSON.stringify err}"
            logger.error err.stack
        else
            for stack in data.StackSummaries
                    msg.send stack.StackName

module.exports = (robot) ->
    robot.hear /List running Cloudformation stacks/i, (msg)->
        msg.send "The following CloudFormation stacks are running:"
        getRegionStacks region, robot.logger, msg for region in defaultRegions.split ','

我希望输出看起来像：

The following CloudFormation stacks are running:
    In region us-east-1:
    demo-container1
    In region us-west-2:
    demo-container2
    In region eu-west-1:
    demo-container3

但是，在函数完成后，回调似乎都被触发了，返回的输出是这样的：

The following CloudFormation stacks are running:
    In region us-east-1:
    In region us-west-2:
    In region eu-west-1:
    demo-container1
    demo-container2
    demo-container3

我确定我忽略了一些简单的事情。有谁知道我做错了什么？

【问题讨论】：

标签： node.js coffeescript hubot

【解决方案1】：

看起来您正在同步打印区域，而 liststacks 函数是异步的。以下内容未经测试，但可能有效：

getRegionStacks = (region, logger, msg) ->
    AWS.config.region = region
    cloudFormation = new AWS.CloudFormation()
    params = {
        StackStatusFilter: [ 'CREATE_COMPLETE' ]
    }
    cloudFormation.listStacks params, (err, data) ->
        if err
            logger.error "Received error #{JSON.stringify err}"
            logger.error err.stack
        else
            msg.send "In region #{region}:"
            for stack in data.StackSummaries
                msg.send stack.StackName

【讨论】：