Node js Basics

src/cli/args.js

@@ -1,5 +1,15 @@
 const parseArgs = () => {
-    // Write your code here 
+    const args = process.argv.slice(2);
+
+    const argsAsArray = [];
+
+    for (let i = 0; i < args.length; i += 2) {
+        argsAsArray.push([args[i].slice(2), args[i + 1]]);
+    }
+
+    const result = argsAsArray.map((ar => `${ar[0]} is ${ar[1]}`)).join(', ');
+
+    console.log(result);
 };
 
 parseArgs();

src/cli/env.js

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

src/cp/cp.js

@@ -1,6 +1,16 @@
+import { spawn } from 'node:child_process';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const spawnChildProcess = async (args) => {
-    // Write your code here
+    const childProcess = spawn('node', [`${__dirname}/files/script.js`, ...args]);
+
+    process.stdin.pipe(childProcess.stdin);
+
+    childProcess.stdout.pipe(process.stdout);
 };
 
-// Put your arguments in function call to test this functionality
-spawnChildProcess( /* [someArgument1, someArgument2, ...] */);
+spawnChildProcess(['firstArg', 'secArg']);

src/fs/copy.js

@@ -1,5 +1,19 @@
+import { existsSync } from 'fs';
+import { cp } from 'fs/promises';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const copy = async () => {
-    // Write your code here 
+    const sourceFolder = `${__dirname}/files`;
+    const destinationFolder = `${__dirname}/files_copy`;
+
+    if (!existsSync(sourceFolder) || existsSync(destinationFolder))
+        throw new Error('FS operation failed');
+
+    await cp(sourceFolder, destinationFolder, { recursive: true });
 };
 
 await copy();

src/fs/create.js

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

src/fs/delete.js

@@ -1,5 +1,18 @@
+import { unlink } from 'fs/promises';
+import { existsSync } from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const remove = async () => {
-    // Write your code here 
+    const deleteFilePath = `${__dirname}/files/fileToRemove.txt`;
+
+    if (!existsSync(deleteFilePath))
+        throw new Error('FS operation failed');
+
+    await unlink(deleteFilePath);
 };
 
 await remove();

src/fs/list.js

@@ -1,5 +1,20 @@
+import { readdir } from 'fs/promises';
+import { existsSync } from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const list = async () => {
-    // Write your code here 
+    const sourceFolder = `${__dirname}/files`;
+
+    if (!existsSync(sourceFolder))
+        throw new Error('FS operation failed');
+
+    const files = await readdir(sourceFolder);
+
+    console.log(files);
 };
 
 await list();

src/fs/read.js

@@ -1,5 +1,20 @@
+import { existsSync } from 'fs';
+import { readFile } from 'fs/promises';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const read = async () => {
-    // Write your code here 
+    const fileToRead = `${__dirname}/files/fileToRead.txt`;
+
+    if (!existsSync(fileToRead))
+        throw new Error('FS operation failed');
+
+    const data = await readFile(fileToRead, 'utf8');
+
+    console.log(data);
 };
 
 await read();

src/fs/rename.js

@@ -1,5 +1,19 @@
+import fs from 'fs/promises';
+import { existsSync } from 'fs';
+import path, { dirname } from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const rename = async () => {
-    // Write your code here 
+    const filePath = `${__dirname}/files/wrongFilename.txt`;
+    const targetFilePath = `${__dirname}/files/properFilename.md`;
+
+    if (!existsSync(filePath) || existsSync(targetFilePath))
+        throw new Error('FS operation failed');
+
+    await fs.rename(filePath, targetFilePath);
 };
 
 await rename();

src/hash/calcHash.js

@@ -1,5 +1,21 @@
+import { createHash } from 'node:crypto'
+import { readFile } from 'fs/promises';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const calculateHash = async () => {
-    // Write your code here 
+    const filePath = `${__dirname}/files/fileToCalculateHashFor.txt`;
+
+    const fileData = await readFile(filePath);
+
+    const hash = createHash('sha256')
+        .update(fileData)
+        .digest('hex');
+
+    console.log(hash);
 };
 
 await calculateHash();

src/modules/esm.mjs

@@ -0,0 +1,40 @@
+import path from "path";
+import os from "os";
+import { createServer } from "http";
+import "./files/c.js";
+
+const random = Math.random();
+
+let unknownObject;
+
+if (random > 0.5) {
+    unknownObject = import("./files/a.json", {
+        assert: { type: "json" }
+    });
+} else {
+    unknownObject = import("./files/b.json", {
+        assert: { type: "json" }
+    });
+}
+
+console.log(`Release ${os.release()}`);
+console.log(`Version ${os.version()}`);
+console.log(`Path segment separator is "${path.sep}"`);
+
+console.log(`Path to current file is ${import.meta.url}`);
+console.log(`Path to current directory is ${path.dirname(import.meta.url)}`);
+
+const myServer = createServer((_, res) => {
+    res.end("Request accepted");
+});
+
+const PORT = 3000;
+
+console.log((await unknownObject).default);
+
+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 +1,18 @@
+import fs from 'fs'
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const read = async () => {
-    // Write your code here 
+    const filePath = `${__dirname}/files/fileToRead.txt`;
+
+    const readableStream = fs.createReadStream(filePath);
+
+    readableStream.on('data', (chunk) => {
+        process.stdout.write(chunk);
+    });
 };
 
 await read();

src/streams/transform.js

@@ -1,5 +1,13 @@
+import { Transform } from 'stream';
+
 const transform = async () => {
-    // Write your code here 
+    const reverse = new Transform({
+        transform(chunk, encoding, callback) {
+            callback(null, chunk.toString().split('').reverse().join(''));
+        }
+    });
+
+    process.stdin.pipe(reverse).pipe(process.stdout);
 };
 
 await transform();

src/streams/write.js

@@ -1,5 +1,18 @@
+import fs from 'fs'
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
 const write = async () => {
-    // Write your code here 
+    const filePath = `${__dirname}/files/fileToWrite.txt`;
+
+    const writableStream = fs.createWriteStream(filePath);
+
+    process.stdin.pipe(writableStream);
+
+    console.log('data to write:')
 };
 
 await write();

src/wt/main.js

@@ -1,5 +1,33 @@
+import os from 'os';
+import { Worker } from 'worker_threads';
+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 workerPath = `${__dirname}/worker.js`;
+    const cpuCount= os.cpus().length
+
+    const processes = [];
+
+    const n = 10;
+
+    for (let i = n; i < n + cpuCount; i++) {
+        processes.push(
+            new Promise((resolve) => {
+                const worker = new Worker(workerPath);
+                worker.postMessage(i);
+                worker.on('message', (result) => resolve({ status: 'resolved', data: result }));
+                worker.on('error', (error) => resolve({ status: error, data: null }));
+            })
+        );
+    }
+
+    const result = await Promise.all(processes);
+
+    console.log(result);
 };
 
 await performCalculations();

src/wt/worker.js

@@ -1,8 +1,13 @@
+import { parentPort } from 'worker_threads';
+
 // n should be received from main thread
 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', (n) => {
+        const result = nthFibonacci(n);
+        parentPort.postMessage(result)
+    });
 };
 
 sendResult();