Prosen-Ghosh

const users = [
  { name: "Alice", age: 25 },
  { name: "Bob", age: 30 },
  { name: "Charlie", age: 35 }
];

const names = users.reduce((acc, {name}) => acc.concat(name), []);
console.log(names);
// Output: ["Alice", "Bob", "Charlie"]

Prosen-Ghosh

const users = [
  { name: "Alice", age: 25 },
  { name: "Bob", age: 30 },
  { name: "Charlie", age: 35 }
];

const names = users.map(user => user.name);
console.log(names); 
// Output: ["Alice", "Bob", "Charlie"]

Prosen-Ghosh

BEGIN ISOLATION LEVEL SERIALIZABLE;
SELECT * FROM users;
COMMIT;

Prosen-Ghosh

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

const options = {
  key: fs.readFileSync('path/to/private.key'),
  cert: fs.readFileSync('path/to/certificate.crt')
};

https.createServer(options, (req, res) => {
  res.writeHead(200);

Prosen-Ghosh

const Redis = require("ioredis");
const redis = new Redis();

app.get("/top-articles", async (req, res) => {
    const articles = await redis.zrevrange("articles", 0, 10);
    res.send(articles.map(JSON.parse));
});

Prosen-Ghosh

const Redis = require("ioredis");
const redis = new Redis();

app.post("/add-article", async (req, res) => {
    const article = req.body;
    await redis.zadd("articles", article.score, JSON.stringify(article));
    res.send("Article added!");
});

Prosen-Ghosh

const Redis = require("ioredis");
const redis = new Redis();

app.get("/receive", async (req, res) => {
    const message = await redis.lpop("messages");
    res.send(`Received message: ${message}`);
});

Prosen-Ghosh

const Redis = require("ioredis");
const redis = new Redis();

app.post("/send", async (req, res) => {
    const message = req.body.message;
    await redis.rpush("messages", message);
    res.send("Message sent!");
});

Prosen-Ghosh

const Redis = require("ioredis");
const redis = new Redis();

app.get("/retention", async (req, res) => {
    const userId = req.query.userId;
    const timestamp = Date.now();
    const bitmapKey = `user_login:${userId}`;
    const offset = Math.floor(timestamp / (24 * 60 * 60 * 1000));

    const retention = await redis.bitcount(bitmapKey, 0, offset);

Prosen-Ghosh

const Redis = require("ioredis");
const redis = new Redis();

app.post("/login", async (req, res) => {
    const userId = req.body.userId;
    const timestamp = Date.now();
    const bitmapKey = `user_login:${userId}`;
    const offset = Math.floor(timestamp / (24 * 60 * 60 * 1000));

    await redis.setbit(bitmapKey, offset, 1);