my answers of https://github.com/workshopper/learnyounode

program-1.js

// # 1
console.log("HELLO WORLD");

program-10.js

// # 10
var http = require("http");
var fs = require("fs");

var server = http.createServer(function(req, res) {
  var rs = fs.createReadStream(process.argv[3]);
  rs.pipe(res);
});
server.listen(process.argv[2]);

program-11.js

// # 11
var http = require("http");
var server = http.createServer(function(req, res) {
  var map = require('through2-map')
  req.pipe(map(function (chunk) {
    return chunk.toString().toUpperCase();
  })).pipe(res);
});
server.listen(process.argv[2]);

program-12.js

// # 12
var http = require("http");
var server = http.createServer(function(req, res) {
  var url = require("url").parse(req.url, true);
  res.writeHead(200, { 'Content-Type': 'application/json' });
  var iso = new Date(url.query.iso);
  if(url.pathname === '/api/parsetime') {
    res.write(JSON.stringify({
      hour: iso.getHours(),
      minute: iso.getMinutes(),
      second: iso.getSeconds()
    }));
  }
  if(url.pathname === '/api/unixtime') {
    res.write(JSON.stringify({unixtime: iso.getTime()}));
  }
  res.end();
});
server.listen(process.argv[2]);

program-2.js

// # 2
var sum = 0;
process.argv.shift();
process.argv.shift();
process.argv.map(function(i) {
  sum += Number(i);
});
console.log(sum);

program-3.js

// # 3
var fs = require("fs");
var content = fs.readFileSync(process.argv[2]).toString();
console.log(content.split('\n').length - 1);

program-4.js

// # 4
var fs = require("fs");
fs.readFile(process.argv[2], function(err, buf) {
  console.log(buf.toString().split('\n').length - 1);
});

program-5.js

// # 5
var fs = require("fs");
var ext = new RegExp("." + process.argv[3] + "$");
fs.readdir(process.argv[2], function(err, list) {
  list.map(function(item) {
    if(ext.test(item)) console.log(item);
  });
});

program-6.js

// # 6

var fs = require("fs");
var path = require("path");

module.exports = function (dir, ext, callback) {
  fs.readdir(dir, function(err, list) {
    if(err) return callback(err);
    var data = list.filter(function(item) {
      if(path.extname(item) === "." + ext) return true;
      else return false;
    });
    return callback(null, data);
  });
};

var mymodule = require('./mymodule.js');
mymodule(process.argv[2], process.argv[3], function(err, list) {
  list.map(function(it) {
    console.log(it);
  });
});

program-7.js

// # 7
var http = require("http");
http.get(process.argv[2], function(res) {
  res.on('data', function(data) {
    console.log(data.toString());
  });
});

program-8.js

// # 8
var http = require("http");
var concatStream = require("concat-stream");
function fetch(url, callback) {
  var data = '';
  http.get(url, function(res) {
    res.pipe(concatStream(function(d) {
      data += d;
    }));
    res.on('end', function() {
      callback(null,data);
    });
  });
}
fetch(process.argv[2], function(err, d1){
  console.log(d1);
  fetch(process.argv[3], function(err, d2) {
    console.log(d2);
    fetch(process.argv[4], function(err, d3) {
      console.log(d3);
    });
  });
});

program-9.js

// # 9
var net =require("net");
var server = net.createServer(function(socket) {
  var date = new Date();
  var year = date.getFullYear()
    , month = date.getMonth() + 1
    , day = date.getDate()
    , hour = date.getHours()
    , min = date.getMinutes();

  socket.end(year + "-" +  ("0"+month).slice(-2)+ "-"+  ("0"+day).slice(-2) + " " +  ("0"+hour).slice(-2) + ":" + min);
});
server.listen(process.argv[2]);