'this' within a prototype offers improvements over the previous microwave example

microwaveImprovedExample.js

(function() {
    "use strict"
    
    function Microwave() {
        this.timer = null
        this.eventListener = null
    }

    Microwave.prototype.start = function(timeMS, callback) {
        this.eventListener = callback
        this.timer = setTimeout((() => {
            this.timer = null
            this.eventListener('done')
        }).bind(this), timeMS)
    }

    Microwave.prototype.stop = function() {
        if (this.timer) {
            clearTimeout(this.timer)
            this.timer = null
            this.eventListener = null
            return true
        } else {
            return false
        }
    }

    Microwave.prototype.isRunning = function() {
        return !!this.timer;
    }

    let microwave = new Microwave();
    let micro2 = new Microwave();
    microwave.start(10000, console.log)
    console.log(microwave.isRunning()) // true
    console.log(micro2.isRunning()) // false
    console.log("stopped: ", microwave.stop()) // stopped: true
    console.log(microwave.isRunning()) // false
    microwave.start(100, console.log) // .... done
})();