const union = (...arr) => [...new Set(arr.flat())];

// Example
union([1, 2], [2, 3], [3]);     // [1, 2, 3]

const gcd = (...arr) => {
  const _gcd = (x, y) => (!y ? x : gcd(y, x % y));
  return [...arr].reduce((a, b) => _gcd(a, b));
};

gcd(8, 36); // 4
gcd(...[12, 8, 32]); // 4

const getURLParameters = url =>
(url.match(/([^?=&]+)(=([^&]*))/g) || []).reduce(
    (a, v) => (
      (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1)), a
    ),
    {}
);

const head = arr => (arr && arr.length ? arr[0] : undefined);

head([1, 2, 3]); // 1
head([]); // undefined
head(null); // undefined
head(undefined); // undefined

require("dotenv").config();
const mongoose = require("mongoose");

const db = process.env.MONGO_URI;

const connectDB = async () => {
	try {
	await mongoose.connect(db, {
	useNewUrlParser: true,
	useUnifiedTopology: true,
	useFindAndModify: false,
	useCreateIndex: true
	});

	console.log("MongoDB Connected");
	} catch (err) {
	console.error(err.message);
	}
};

module.exports = connectDB;

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