GoF Singleton Pattern

Singleton.js

class Database {
    constructor(url) {
        this.url = url;    
    }
    
    static getInstance() {
        if (typeof Database.instance === 'object') {
          return Database.instance;
        }
        Database.instance = new Database('http//localhost:8545');
        return Database.instance;
    }
}

const instance1 = Database.getInstance();
const instance2 = Database.getInstance();

console.log('Is the same? ', instance1 === instance2); 
// Is the same?  true