var async = require('async');
console.time('series');
async.series({
  one: function(callback) {
    callback(null, 'one');//callback('i am err','one');异常处理
  },
  two: function(callback) {
    callback(null, 'two');

  },
}, function(error, result) {
  //最后结果
  console.log('error: ' + error);
  console.log('result: ' + result);
  console.timeEnd('series');
});

// error: null
// result: [object Object]
// series: 4.472ms

async.waterfall([
  myFirstFun,
  mySecondFun,
  myLastFun
],function(err,result) { // result回调函数
  // result 相当于tasks数组中最后一个函数（myLastFun）的返回值done
  console.log(result);  // myLastFun
})
function myFirstFun(callback) {
  callback(null,'one','two');
}
function mySecondFun(arg1,arg2,callback) {
  // arg1 相当于 'one' ,arg2 相当于 'two'
  callback(null,'three');
}
function myLastFun(arg1,callback) {
  // arg1 相当于 'three'
  callback(null,'done');
}

async.parallel([
  function(callback) {
    setTimeout(function() {
      callback(null, 'one');
    }, 200);
  },
  function(callback) {
    setTimeout(function() {
      callback(null, 'two');
    }, 100);
  }
],function(err, results) {
  console.log(result)}
);

var async = require('async');
console.time('auto');
async.auto({
  getData: function(callback) {
    setTimeout(function() {
      console.log('1.1: got data');
      callback(null, 'mydata');
    }, 300);
  },
  makeFolder: function(callback) {
    setTimeout(function() {
      console.log('1.1: made folder');
      callback(null, 'myfolder');
    }, 200);
  },
  writeFile: ['getData', 'makeFolder', function(callback) {
    setTimeout(function() {
      console.log('1.1: wrote file');
      callback(null, 'myfile');
    }, 300);
  }],
  emailFiles: ['writeFile', function(callback, results) {
    console.log('emailed file: ', results.writeFile);
    callback(null, results.writeFile);
  }]
}, function(err, results) {
  console.log('err: ', err);
  console.log('results: ', results);
  console.timeEnd('auto');
});