Node Basics

src/cli/args.js

@@ -1,5 +1,14 @@
 const parseArgs = () => {
-  // Write your code here
+  const args = process.argv.slice(2);
+  const result = [];
+
+  for (let i = 0; i < args.length; i += 2) {
+    const prop = args[i].replace('--', '');
+    const value = args[i + 1];
+    result.push(`${prop} is ${value}`);
+  }
+
+  console.log(result.join(', '));
 };
 
 parseArgs();

src/cli/env.js

@@ -1,5 +1,11 @@
 const parseEnv = () => {
-  // Write your code here
+  const prefix = 'RSS_';
+  const envVars = Object.entries(process.env)
+    .filter(([key]) => key.startsWith(prefix))
+    .map(([key, value]) => `${key}=${value}`)
+    .join('; ');
+
+  console.log(envVars);
 };
 
 parseEnv();

src/cp/cp.js

@@ -1,6 +1,15 @@
+import { spawn } from 'child_process';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
 const spawnChildProcess = async (args) => {
-  // Write your code here
+  const __filename = fileURLToPath(import.meta.url);
+  const __dirname = path.dirname(__filename);
+
+  const child = spawn('node', [path.join(__dirname, 'files', 'script.js'), ...args]);
+
+  child.stdout.pipe(process.stdout);
+  process.stdin.pipe(child.stdin);
 };
 
-// Put your arguments in function call to test this functionality
-spawnChildProcess( /* [someArgument1, someArgument2, ...] */);
+spawnChildProcess(['arg1', 'arg2', 'arg3']);

src/fs/copy.js

@@ -1,5 +1,22 @@
+import { cp } from 'fs/promises';
+import { access } from 'fs/promises';
+
 const copy = async () => {
-  // Write your code here
+  try {
+    await access('./src/fs/files');
+    try {
+      await access('./src/fs/files_copy');
+      throw new Error('FS operation failed');
+    } catch (err) {
+      if (err.code === 'ENOENT') {
+        await cp('./src/fs/files', './src/fs/files_copy', { recursive: true });
+      } else {
+        throw new Error('FS operation failed');
+      }
+    }
+  } catch (err) {
+    throw new Error('FS operation failed');
+  }
 };
 
 await copy();

src/fs/create.js

@@ -1,5 +1,11 @@
+import { writeFile } from 'fs/promises';
+
 const create = async () => {
-  // Write your code here
+  try {
+    await writeFile('./src/fs/files/fresh.txt', 'I am fresh and young', { flag: 'wx' });
+  } catch (err) {
+    throw new Error('FS operation failed');
+  }
 };
 
 await create();

src/fs/delete.js

@@ -1,5 +1,13 @@
+import { unlink } from 'fs/promises';
+import { access } from 'fs/promises';
+
 const remove = async () => {
-  // Write your code here
+  try {
+    await access('./src/fs/files/fileToRemove.txt');
+    await unlink('./src/fs/files/fileToRemove.txt');
+  } catch (err) {
+    throw new Error('FS operation failed');
+  }
 };
 
 await remove();

src/fs/files/fresh.txt

@@ -0,0 +1 @@
+I am fresh and young

src/fs/files_copy/dontLookAtMe.txt

@@ -0,0 +1 @@
+What are you looking at?!

src/fs/files_copy/fileToRead.txt

@@ -0,0 +1,7 @@
+My content
+should
+be
+printed
+into
+console
+!

src/fs/files_copy/fileToRemove.txt

@@ -0,0 +1 @@
+How dare you!

src/fs/files_copy/fresh.txt

@@ -0,0 +1 @@
+I am fresh and young

src/fs/files_copy/hello.txt

@@ -0,0 +1 @@
+Hello Node.js

src/fs/files_copy/wrongFilename.txt

@@ -0,0 +1,3 @@
+# This is a file with a wrong filename
+
+Hello from **markdown**!

src/fs/list.js

@@ -1,5 +1,14 @@
+import { readdir } from 'fs/promises';
+import { access } from 'fs/promises';
+
 const list = async () => {
-  // Write your code here
+  try {
+    await access('./src/fs/files');
+    const files = await readdir('./src/fs/files');
+    console.log(files);
+  } catch (err) {
+    throw new Error('FS operation failed');
+  }
 };
 
 await list();

src/fs/read.js

@@ -1,5 +1,14 @@
+import { readFile } from 'fs/promises';
+import { access } from 'fs/promises';
+
 const read = async () => {
-  // Write your code here
+  try {
+    await access('./src/fs/files/fileToRead.txt');
+    const content = await readFile('./src/fs/files/fileToRead.txt', { encoding: 'utf8' });
+    console.log(content);
+  } catch (err) {
+    throw new Error('FS operation failed');
+  }
 };
 
 await read();

src/fs/rename.js

@@ -1,5 +1,21 @@
+import { rename as renameFile, access } from 'fs/promises';
+
 const rename = async () => {
-  // Write your code here
+  try {
+    await access('./src/fs/files/wrongFilename.txt');
+    try {
+      await access('./src/fs/files/properFilename.md');
+      throw new Error('FS operation failed');
+    } catch (err) {
+      if (err.code === 'ENOENT') {
+        await renameFile('./src/fs/files/wrongFilename.txt', './src/fs/files/properFilename.md');
+      } else {
+        throw new Error('FS operation failed');
+      }
+    }
+  } catch (err) {
+    throw new Error('FS operation failed');
+  }
 };
 
 await rename();

src/hash/calcHash.js

@@ -1,5 +1,17 @@
+import { createReadStream } from 'fs';
+import { createHash } from 'crypto';
+
 const calculateHash = async () => {
-  // Write your code here
+  const hash = createHash('sha256');
+  const stream = createReadStream('./src/hash/files/fileToCalculateHashFor.txt');
+
+  stream.on('data', (data) => {
+    hash.update(data);
+  });
+
+  stream.on('end', () => {
+    console.log(hash.digest('hex'));
+  });
 };
 
 await calculateHash();

src/modules/esm.mjs

@@ -0,0 +1,43 @@
+import path from 'node:path';
+import os from 'node:os';
+import { createServer } from 'node:http';
+import { fileURLToPath } from 'node:url';
+import { readFile } from 'fs/promises';
+
+import './files/c.cjs';
+
+const random = Math.random();
+
+const aJson = JSON.parse(await readFile('./src/modules/files/a.json', 'utf8'));
+const bJson = JSON.parse(await readFile('./src/modules/files/b.json', 'utf8'));
+
+const unknownObject = random > 0.5 ? aJson : bJson;
+
+console.log(`Release ${os.release()}`);
+console.log(`Version ${os.version()}`);
+console.log(`Path segment separator is "${path.sep}"`);
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+console.log(`Path to current file is ${__filename}`);
+console.log(`Path to current directory is ${__dirname}`);
+
+const myServer = createServer((_, res) => {
+  res.end('Request accepted');
+});
+
+const PORT = 3000;
+
+console.log(unknownObject);
+
+myServer.listen(PORT, () => {
+  console.log(`Server is listening on port ${PORT}`);
+  console.log('To terminate it, use Ctrl+C combination');
+});
+
+export {
+  unknownObject,
+  myServer,
+};
+

src/streams/read.js

@@ -1,5 +1,8 @@
+import { createReadStream } from 'fs';
+
 const read = async () => {
-  // Write your code here
+  const stream = createReadStream('./src/streams/files/fileToRead.txt');
+  stream.pipe(process.stdout);
 };
 
 await read();

src/streams/transform.js

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

src/streams/write.js

@@ -1,5 +1,8 @@
+import { createWriteStream } from 'fs';
+
 const write = async () => {
-  // Write your code here
+  const stream = createWriteStream('./src/streams/files/fileToWrite.txt');
+  process.stdin.pipe(stream);
 };
 
 await write();

src/wt/main.js

@@ -1,5 +1,42 @@
+import { Worker } from 'worker_threads';
+import { cpus } from 'os';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const performCalculations = async () => {
-  // Write your code here
+  const cpuCount = cpus().length;
+  console.log(`Number of CPU cores: ${cpuCount}`);
+
+  const workers = [];
+
+  for (let i = 0; i < cpuCount; i++) {
+    const worker = new Worker(path.join(__dirname, 'worker.js'));
+    workers.push(worker);
+  }
+
+  const promises = workers.map((worker, i) => {
+    return new Promise((resolve) => {
+      const data = 10 + i;
+      worker.postMessage(data);
+
+      worker.on('message', (message) => {
+        resolve({ status: 'resolved', data: message });
+      });
+
+      worker.on('error', () => {
+        resolve({ status: 'error', data: null });
+      });
+    });
+  });
+
+  const results = await Promise.all(promises);
+
+  workers.forEach(worker => worker.terminate());
+
+  console.log(results);
 };
 
 await performCalculations();

src/wt/worker.js

@@ -1,8 +1,12 @@
-// n should be received from main thread
+import { parentPort } from 'worker_threads';
+
 const nthFibonacci = (n) => n < 2 ? n : nthFibonacci(n - 1) + nthFibonacci(n - 2);
 
 const sendResult = () => {
-  // This function sends result of nthFibonacci computations to main thread
+  parentPort.on('message', (data) => {
+    const result = nthFibonacci(data);
+    parentPort.postMessage(result);
+  });
 };
 
 sendResult();

src/zip/compress.js

@@ -1,5 +1,13 @@
+import { createReadStream, createWriteStream } from 'fs';
+import { createGzip } from 'zlib';
+import { pipeline } from 'stream/promises';
+
 const compress = async () => {
-  // Write your code here
+  const source = createReadStream('./src/zip/files/fileToCompress.txt');
+  const destination = createWriteStream('./src/zip/files/archive.gz');
+  const gzip = createGzip();
+
+  await pipeline(source, gzip, destination);
 };
 
 await compress();