Nodejs basics

src/cli/args.js

@@ -1,5 +1,16 @@
 const parseArgs = () => {
-  // Write your code here
+  const args = process.argv.slice(2);
+
+  const result = [];
+
+  for (let i = 0; i < args.length; i += 2) {
+    const propName = args[i].replace('--', '');
+    const value = args[i + 1];
+
+    result.push(`${propName} is ${value}`);
+  }
+
+  console.log(result.join(', '));
 };
 
 parseArgs();

src/cli/env.js

@@ -1,5 +1,12 @@
 const parseEnv = () => {
-  // Write your code here
+  const envVars = process.env;
+
+  const result = Object.entries(envVars)
+    .filter(([key]) => key.startsWith('RSS_'))
+    .map(([key, value]) => `${key}=${value}`)
+    .join('; ');
+
+  console.log(result);
 };
 
 parseEnv();

src/cp/cp.js

@@ -1,6 +1,28 @@
+import { spawn } from 'node:child_process';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const spawnChildProcess = async (args) => {
-  // Write your code here
+  const childScript = path.resolve(__dirname, 'files', 'script.js');
+
+  const child = spawn('node', [childScript, ...args], {
+    stdio: ['pipe', 'pipe', 'inherit'],
+  });
+
+  process.stdin.pipe(child.stdin);
+
+  child.stdout.pipe(process.stdout);
+
+  child.on('close', (code) => {
+    console.log(`\nChild process exited with code ${code}`);
+  });
+
+  child.on('error', (err) => {
+    console.error('Failed to start child process:', err);
+  });
 };
 
-// Put your arguments in function call to test this functionality
-spawnChildProcess( /* [someArgument1, someArgument2, ...] */);
+spawnChildProcess(['smth', 'bbb']);

src/fs/copy.js

@@ -1,5 +1,23 @@
+import { cp } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const copy = async () => {
-  // Write your code here
+  try {
+    const src = path.resolve(__dirname, 'files');
+    const dest = path.resolve(__dirname, 'files_copy');
+
+    await cp(src, dest, {
+      recursive: true,
+      errorOnExist: true,
+      force: false,
+    });
+  } catch {
+    throw new Error('FS operation failed');
+  }
 };
 
 await copy();

src/fs/create.js

@@ -1,5 +1,18 @@
+import { writeFile } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const create = async () => {
-  // Write your code here
+  try {
+    const filePath = path.resolve(__dirname, 'files', 'fresh.txt');
+
+    await writeFile(filePath, 'I am fresh and young', { flag: 'wx' });
+  } catch {
+    throw new Error('FS operation failed');
+  }
 };
 
 await create();

src/fs/delete.js

@@ -1,5 +1,20 @@
+import { rm, access } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const remove = async () => {
-  // Write your code here
+  try {
+    const filePath = path.resolve(__dirname, 'files', 'fileToRemove.txt');
+
+    await access(filePath);
+
+    await rm(filePath);
+  } catch {
+    throw new Error('FS operation failed');
+  }
 };
 
 await remove();

src/fs/list.js

@@ -1,5 +1,20 @@
+import { readdir } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const list = async () => {
-  // Write your code here
+  try {
+    const folderPath = path.resolve(__dirname, 'files');
+
+    const files = await readdir(folderPath);
+
+    console.log(files);
+  } catch {
+    throw new Error('FS operation failed');
+  }
 };
 
 await list();

src/fs/read.js

@@ -1,5 +1,20 @@
+import { readFile } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const read = async () => {
-  // Write your code here
+  try {
+    const filePath = path.resolve(__dirname, 'files', 'fileToRead.txt');
+
+    const content = await readFile(filePath, 'utf-8');
+
+    console.log(content);
+  } catch {
+    throw new Error('FS operation failed');
+  }
 };
 
 await read();

src/fs/rename.js

@@ -1,5 +1,26 @@
+import { rename as fsRename, access } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const rename = async () => {
-  // Write your code here
+  try {
+    const srcPath = path.resolve(__dirname, 'files', 'wrongFilename.txt');
+    const destPath = path.resolve(__dirname, 'files', 'properFilename.md');
+
+    await access(srcPath);
+
+    try {
+      await access(destPath);
+      throw new Error();
+    } catch {}
+
+    await fsRename(srcPath, destPath);
+  } catch {
+    throw new Error('FS operation failed');
+  }
 };
 
 await rename();

src/hash/calcHash.js

@@ -1,5 +1,31 @@
+import { createReadStream } from 'node:fs';
+import { createHash } from 'node:crypto';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const calculateHash = async () => {
-  // Write your code here
+  const filePath = path.resolve(
+    __dirname,
+    'files',
+    'fileToCalculateHashFor.txt',
+  );
+
+  return new Promise((resolve, reject) => {
+    const hash = createHash('sha256');
+    const stream = createReadStream(filePath);
+
+    stream.on('error', () => reject(new Error('FS operation failed')));
+
+    stream.on('data', (chunk) => hash.update(chunk));
+
+    stream.on('end', () => {
+      console.log(hash.digest('hex'));
+      resolve();
+    });
+  });
 };
 
 await calculateHash();

src/modules/cjsToEsm.cjs → src/modules/esm.mjs

@@ -1,12 +1,19 @@
-const path = require('node:path');
-const { release, version } = require('node:os');
-const { createServer: createServerHttp } = require('node:http');
+import path from 'node:path';
+import { release, version } from 'node:os';
+import { createServer as createServerHttp } from 'node:http';
+import { fileURLToPath } from 'node:url';
 
-require('./files/c.cjs');
+import './files/c.cjs';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
 
 const random = Math.random();
 
-const unknownObject = random > 0.5 ? require('./files/a.json') : require('./files/b.json');
+const unknownObject =
+  random > 0.5
+    ? (await import('./files/a.json', { with: { type: 'json' } })).default
+    : (await import('./files/b.json', { with: { type: 'json' } })).default;
 
 console.log(`Release ${release()}`);
 console.log(`Version ${version()}`);
@@ -28,7 +35,4 @@ myServer.listen(PORT, () => {
   console.log('To terminate it, use Ctrl+C combination');
 });
 
-module.exports = {
-  unknownObject,
-  myServer,
-};
+export { unknownObject, myServer };

src/streams/read.js

@@ -1,5 +1,20 @@
+import { createReadStream } from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const read = async () => {
-  // Write your code here
+  const filePath = path.resolve(__dirname, 'files', 'fileToRead.txt');
+
+  const readable = createReadStream(filePath);
+
+  readable.on('error', () => {
+    throw new Error('FS operation failed');
+  });
+
+  readable.pipe(process.stdout);
 };
 
 await read();

src/streams/transform.js

@@ -1,5 +1,14 @@
+import { Transform } from 'node:stream';
+
 const transform = async () => {
-  // Write your code here
+  const reverseStream = new Transform({
+    transform(chunk, _, callback) {
+      const reversed = chunk.toString().split('').reverse().join('');
+      callback(null, reversed);
+    },
+  });
+
+  process.stdin.pipe(reverseStream).pipe(process.stdout);
 };
 
 await transform();

src/streams/write.js

@@ -1,5 +1,16 @@
+import { createWriteStream } from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const write = async () => {
-  // Write your code here
+  const filePath = path.resolve(__dirname, 'files', 'fileToWrite.txt');
+
+  const writable = createWriteStream(filePath);
+
+  process.stdin.pipe(writable);
 };
 
 await write();

src/wt/main.js

@@ -1,5 +1,35 @@
+import { Worker } from 'node:worker_threads';
+import os from 'node:os';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const performCalculations = async () => {
-  // Write your code here
+  const numCPUs = os.cpus().length;
+  const results = [];
+  const workers = [];
+
+  for (let i = 0; i < numCPUs; i++) {
+    const worker = new Worker(path.resolve(__dirname, 'worker.js'));
+    workers.push(worker);
+
+    const n = 10 + i;
+
+    const promise = new Promise((resolve) => {
+      worker.once('message', (msg) => resolve(msg));
+      worker.once('error', () => resolve({ status: 'error', data: null }));
+    });
+
+    worker.postMessage(n);
+    results.push(promise);
+  }
+
+  const finalResults = await Promise.all(results);
+  console.log(finalResults);
+
+  workers.forEach((w) => w.terminate());
 };
 
 await performCalculations();

src/wt/worker.js

@@ -1,8 +1,27 @@
-// n should be received from main thread
-const nthFibonacci = (n) => n < 2 ? n : nthFibonacci(n - 1) + nthFibonacci(n - 2);
+import { parentPort } from 'node:worker_threads';
+
+const nthFibonacci = (n) =>
+  n < 2 ? n : nthFibonacci(n - 1) + nthFibonacci(n - 2);
+
+let lastResult = null;
 
 const sendResult = () => {
-  // This function sends result of nthFibonacci computations to main thread
+  if (parentPort && lastResult !== null) {
+    parentPort.postMessage(lastResult);
+  }
 };
 
+if (parentPort) {
+  parentPort.on('message', (n) => {
+    try {
+      const fib = nthFibonacci(n);
+      lastResult = { status: 'resolved', data: fib };
+      sendResult();
+    } catch (err) {
+      lastResult = { status: 'error', data: null };
+      sendResult();
+    }
+  });
+}
+
 sendResult();