Create Instances and Singletons

ModuleExample.js

let api = function Binance() {
    let self = this;

    self.cache = 0;
    
    return {
        setCache: function(val) {
            self.cache = val;
        },
        getCache: function() {
            return self.cache;
        }
    };
};

module.exports = api;

SingletonAndInstance.js

const api = require('./ModuleExample');
const api2 = require('./ModuleExample');

let singleton1 = api();
let singleton2 = api2();
let instance1 = new api();
let instance2= new api();

// Set value of singleton
singleton1.setCache('this can be overridden');
// Set other value of the same singleton even though it was created somewhere else
singleton2.setCache('see I overrode the previous value');

// Set value of instance
instance1.setCache('other stuff');
// Set value of another separate instance
instance2.setCache('different stuff');


console.log(singleton1.getCache()); //see I overrode the previous value
console.log(singleton2.getCache()); //see I overrode the previous value
console.log(instance1.getCache());  //other stuff
console.log(instance2.getCache());  //different stuff