http://point.davidglasser.net/2013/06/27/surprising-javascript-memory-leak.html

gistfile1.js

var theThing = null;
var replaceThing = function () {
    var originalThing = theThing;
    var unused = function () {
    if (originalThing)
        console.log("hi");
    };
    theThing = {
        longStr: new Array(1000000).join('*'),
        someMethod: function () {}
    };
};
setInterval(replaceThing, 1000);