NodeSchool之learnyounode

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learnyounode是NodeSchool里介绍基本异步编程的课程，通过13个简单的练习可以学习异步io，http等知识。运行此课程使用如下命令

npm install -g learnyounode  #安装

learnyounode 运行

为方便以后复习，现将每一个练习的代码整理如下

hello_world（你好，世界）

console.log("HELLO WORLD")

baby_steps（婴儿学步）

//此例子演示从命令行接受参数的方法var result = 0
//process.argv[0]是node，process.argv[1]是脚本文件名，所以从2开始才是输入参数
for (var i = 2; i < process.argv.length; i++)
  result += Number(process.argv[i])

console.log(result)

my_first_io（第一个 I/O）

var fs = require(‘fs‘)

//使用同步的方式读取文件，返回值是一个Buffer对象

var contents = fs.readFileSync(process.argv[2])
var lines = contents.toString().split(‘\n‘).length - 1
console.log(lines)

my_first_async_io（第一个异步 I/O）

var fs = require(‘fs‘)
var file = process.argv[2]

fs.readFile(file, function (err, contents) {
  // fs.readFile(file, ‘utf8‘, callback) can also be used
  var lines = contents.toString().split(‘\n‘).length - 1
  console.log(lines)
})

filtered_ls（LS 过滤器）

var fs = require(‘fs‘)
var path = require(‘path‘)

//异步的方式读取目录文件，详情http://nodejs.org/api/fs.html#fs_fs_readdir_path_callback

fs.readdir(process.argv[2], function (err, list) {
  list.forEach(function (file) {
    if (path.extname(file) === ‘.‘ + process.argv[3])
      console.log(file)
  })
})

make_it_modular（使其模块化）

solution.js

var filterFn = require(‘./solution_filter.js‘)
var dir = process.argv[2]
var filterStr = process.argv[3]

filterFn(dir, filterStr, function (err, list) {
  if (err)
    return console.error(‘There was an error:‘, err)

  list.forEach(function (file) {
    console.log(file)
  })
})

solution_filter.js

var fs = require(‘fs‘)
var path = require(‘path‘)

module.exports = function (dir, filterStr, callback) {

  fs.readdir(dir, function (err, list) {
    if (err)
      return callback(err)

    list = list.filter(function (file) {
      return path.extname(file) === ‘.‘ + filterStr
    })

    callback(null, list)
  })
}

http_client（HTTP 客户端）

var http = require(‘http‘)
//http://nodejs.org/api/http.html#http_http_get_options_callback
http.get(process.argv[2], function (response) {
  response.setEncoding(‘utf8‘)
  response.on(‘data‘, console.log)
  response.on(‘error‘, console.error)
})

http_collect（HTTP 收集器）

//运行此例子需要安装bl

// npm install bl

var http = require(‘http‘)
var bl = require(‘bl‘)

http.get(process.argv[2], function (response) {
  response.pipe(bl(function (err, data) {
    if (err)
      return console.error(err)
    data = data.toString()
    console.log(data.length)
    console.log(data)
  }))  
})

juggling_async（玩转异步）

var http = require(‘http‘)
var bl = require(‘bl‘)
var results = []
var count = 0

function printResults () {
  for (var i = 0; i < 3; i++)
    console.log(results[i])
}

function httpGet (index) {
  http.get(process.argv[2 + index], function (response) {
    response.pipe(bl(function (err, data) {
      if (err)
        return console.error(err)

      results[index] = data.toString()
      count++

      if (count == 3)
        printResults()
    }))
  })
}

for (var i = 0; i < 3; i++)
  httpGet(i)

time_server（授时服务器）

var net = require(‘net‘)

function zeroFill(i) {
  return (i < 10 ? ‘0‘ : ‘‘) + i
}

function now () {
  var d = new Date()
  return d.getFullYear() + ‘-‘
    + zeroFill(d.getMonth() + 1) + ‘-‘
    + zeroFill(d.getDate()) + ‘ ‘
    + zeroFill(d.getHours()) + ‘:‘
    + zeroFill(d.getMinutes())
}

var server = net.createServer(function (socket) {
  socket.end(now() + ‘\n‘)
})

server.listen(Number(process.argv[2]))

http_file_server（HTTP 文件服务器）

var http = require(‘http‘)
var fs = require(‘fs‘)

var server = http.createServer(function (req, res) {
  res.writeHead(200, { ‘content-type‘: ‘text/plain‘ })

  fs.createReadStream(process.argv[3]).pipe(res)
})

server.listen(Number(process.argv[2]))

 

HTTP 大写转换器（HTTP 大写转换器）

 

var http = require(‘http‘)
var map = require(‘through2-map‘)

var server = http.createServer(function (req, res) {
  if (req.method != ‘POST‘)
    return res.end(‘send me a POST\n‘)

  req.pipe(map(function (chunk) {
    return chunk.toString().toUpperCase()
  })).pipe(res)
})

server.listen(Number(process.argv[2]))

http_json_api_server（HTTP JSON API 服务器）

var http = require(‘http‘)
var url = require(‘url‘)

function parsetime (time) {
  return {
    hour: time.getHours(),
    minute: time.getMinutes(),
    second: time.getSeconds()
  }
}

function unixtime (time) {
  return { unixtime : time.getTime() }
}

var server = http.createServer(function (req, res) {
  var parsedUrl = url.parse(req.url, true)
  var time = new Date(parsedUrl.query.iso)
  var result

  if (/^\/api\/parsetime/.test(req.url))
    result = parsetime(time)
  else if (/^\/api\/unixtime/.test(req.url))
    result = unixtime(time)

  if (result) {
    res.writeHead(200, { ‘Content-Type‘: ‘application/json‘ })
    res.end(JSON.stringify(result))
  } else {
    res.writeHead(404)
    res.end()
  }
})
server.listen(Number(process.argv[2]))

NodeSchool之learnyounode

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原文地址：http://www.cnblogs.com/sunchey/p/4252770.html