myleak.js

var Leaker = function() {};
Leaker.prototype = {
    init: function(name){
        this._interval = null;
        this.start();
        this.name = name;
    },
    start: function() {
        var self = this;
        this._interval = setInterval(function() {
            self.onInterval(); 
        }, 100);
    },
    destroy: function() {
        if (this._interval !== null) {
            clearInterval(this._interval);
        }
    },
    onInterval: function() {
        console.log("Interval: " + this.name);
    }
};

var leak;

document.getElementById('start_button').addEventListener('click', function() {
    if (leak !== undefined) {
        return;
    }
    leak = new Leaker();
    leak.init('test');
}, false);

document.getElementById('destroy_button').addEventListener('click', function() {
    leak = null;          
}, false);