//自定义函数，包含回调函数
var getUser=(id,callback)=>{
 var user = {
   id:id,
   name:'jonson'
 }
 setTimeout(()=>{
   callback(user);
 },3000);
}

//调用，并且传递了一个回调函数
getUser(31,(userobject)=>{
 console.log(userobject);
})

{ id: 31, name: 'jonson' }

> npm install --save request

const request = require('request');

request({
 url:'https://api.openweathermap.org/data/2.5/forecast?q=beijing,cn&appid=09ec05ac89602c9970393fe760db2bf5',
 json:true   // 将json返回结果解析为json对象
},(error,response,body)=>{
 console.log(body);
});

{ cod: '200',
 message: 0.0038,
 cnt: 38,
 list:
  [ { dt: 1542261600,
      main: [Object],
      weather: [Array],
      clouds: [Object],
      wind: [Object],
      rain: [Object],
      sys: [Object],
      dt_txt: '2018-11-15 06:00:00' },
    { dt: 1542272400,
      main: [Object],
      weather: [Array],
      clouds: [Object],
      wind: [Object],
      rain: [Object],
      sys: [Object],
      dt_txt: '2018-11-15 09:00:00' },

     ...

const request = require('request');

request({
 url:'https://api.openweathermap.org/data/2.5/forecast?q=beijing,cn&appid=09ec05ac89602c9970393fe760db2bf5',
 json:true   // 将返回结果解析为json对象
},(error,response,body)=>{
 console.log(JSON.stringify(body,undefined,2));
});

{
 "cod": "200",
 "message": 0.0026,
 "cnt": 38,
 "list": [
   {
     "dt": 1542261600,
     "main": {
       "temp": 282.38,
       "temp_min": 277.973,
       "temp_max": 282.38,
       "pressure": 1017.9,
       "sea_level": 1043.48,
       "grnd_level": 1017.9,
       "humidity": 90,
       "temp_kf": 4.4
     },
     "weather": [
       {
         "id": 500,
         "main": "Rain",
         "description": "light rain",
         "icon": "10d"
       }
     ],
     "clouds": {
       "all": 92
     },
     "wind": {
       "speed": 1.71,
       "deg": 330.5
     },
     "rain": {
       "3h": 0.98
     },
     "sys": {
       "pod": "d"
     },
     "dt_txt": "2018-11-15 06:00:00"
   },

const request = require('request');
const yargs = require('yargs');

const argv = yargs.options({
 a:{
   demand:true,
   alias:'address',
   describe:'Address to fetch weather for',
   string:true
 }
})
.help()
.alias('help','h')
.argv;

request({
 url:`https://samples.openweathermap.org/data/2.5/forecast?q=${argv.address},cn&appid=b6907d289e10d714a6e88b30761fae22`,
 json:true   // 将返回结果解析为json对象
},(error,response,body)=>{
 console.log(JSON.stringify(body,undefined,2));
});

> node async.js -a xingjiang