my learnyounode solutions

01_introduction.js

console.log('HELLO WORLD');

02_baby_steps.js

let args = process.argv.slice(2);

let sum = 0;

for (var i = args.length - 1; i >= 0; i--) {
  sum += +args[i];
}

console.log(sum);

// var result = 0

// for (var i = 2; i < process.argv.length; i++) {
//   result += Number(process.argv[i])
// }

// console.log(result)

03_first_io.js

const fs = require('fs');
const path = process.argv[2];
const file = fs.readFileSync(path);
const fileContent = file.toString();

console.log(fileContent.split('\n').length - 1);

04_async_io.js

const fs = require('fs');
const path = process.argv[2];

fs.readFile(path, 'utf8', (err, data) => {
  if (err) return console.log(err);

  const lines = data.split('\n').length - 1;
  console.log(lines);
});

05_filtered_ls.js

const fs = require('fs');
const path = require('path');
const pathArg = process.argv[2];
const extArg = process.argv[3];

fs.readdir(pathArg, (err, files) => {
  if (err) return console.log(err);

  files.forEach( function(file) {
    if (path.extname(file).includes(extArg)) {
      console.log(file);
    }
  });
});

06_modular_1.js

const pathArg = process.argv[2];
const extArg = process.argv[3];
const filter = require('./06_modular_2.js');

filter(pathArg, extArg, (err, filteredFiles) => {
  if (err) return console.error(err);

  filteredFiles.forEach((file) => {
    console.log(file);
  });
});

06_modular_2.js

const fs = require('fs');
const path = require('path');

module.exports = function (dir, ext, callback) {
  fs.readdir(dir, (err, files) => {
    if (err) return callback(err);

    files = files.filter((file) => {
      return path.extname(file).includes(ext);
    });

    callback(null, files);
  });
}

07_http_client.js

const http = require('http');

const url = process.argv[2];

http.get(url, (response) => {
  response.setEncoding('utf8');
  // verbose callback
  response.on('data', (data) => { console.log(data); });
  // simple callback
  response.on('error', console.error);
});

08_http_collect.js

const http = require('http');
const url = process.argv[2];

http.get(url, (response) => {
  response.setEncoding('utf8');

  let rawData = '';

  response.on('error', console.error);

  response.on('data', (chunk) => {
    rawData += chunk;
  });

  response.on('end', (data) => {
    console.log(rawData.length);
    console.log(rawData);
  });
});

09_juggling_async.js

const http = require('http');
const args = process.argv.slice(2);

function collectData (url, callback) {
  http.get(url, (response) => {
    response.setEncoding('utf8');

    let rawData = '';

    response.on('error', (error) => callback(error));
    
    response.on('data', (chunk) => {
      rawData += chunk;
    });

    response.on('end', (data) => {
      callback(null, rawData);
    });
  });
}

var argCount = args.length;
let allData = {};

args.forEach((url, index) => {
  collectData(url, (err, data) => {
    allData[index] = data;
    argCount--;
    if (argCount <= 0) {
      Object.keys(allData).map(key => console.log(allData[key]))
    }
  });
});

10_time_server.js

const net = require('net');
const port = process.argv[2];

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

function now() {
  const date = new Date();
  return date.getFullYear() + '-' +
    zeroFill(date.getMonth() + 1) + '-' +
    zeroFill(date.getDate()) + ' ' +
    zeroFill(date.getHours()) + ':' +
    zeroFill(date.getMinutes());
}

const server = net.createServer((connection) => {  
  connection.end(now() + '\n');
});

server.on('error', (err) => {
  throw err;
});

server.listen(+port);

11_http_file_server.js

const http = require('http');
const fs = require('fs');
const port = process.argv[2];
const path = process.argv[3];

const server = http.createServer((request, response) => {
  response.writeHead(200, {'content-type': 'text/plain'});
  fs.createReadStream(path).pipe(response);
});

server.on('error', (err) => {
  throw err;
});

server.listen(+port);

12_http_uppercaserer.js

const http = require('http');
const map = require('through2-map');
const port = process.argv[2];

const server = http.createServer((request, response) => {
  if (request.method !== 'POST') return response.end('Request is not POST!\n');

  request.pipe(map((chunk) => {
    return chunk.toString().toUpperCase();
  })).pipe(response);
});

server.on('error', (err) => {
  throw err;
});

server.listen(+port);

13_http_json_api_server.js

const http = require('http');
const url = require('url');
const port = process.argv[2];

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

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

const server = http.createServer((request, response) => {
  if (request.method !== 'GET') return response.end('Request is not GET!\n');
  const URLobj = url.parse(request.url, true);
  const time = new Date(URLobj.query.iso);
  let result;

  if (URLobj.pathname === '/api/parsetime') {
    result = parseTime(time);
  }

  if (URLobj.pathname === '/api/unixtime') {
    result = unixTime(time);
  }

  response.writeHead(200, {'content-type': 'application/json'});
  response.end(JSON.stringify(result));
});

server.on('error', (err) => {
  throw err;
});

server.listen(+port);