How to Implement DOM Data Binding in Pure JavaScript

data-binding.js

// http://stackoverflow.com/a/16484266/754377
function DataBind(element, data) {
    this.data = data;
    this.element = element;
    element.value = data;
    element.addEventListener("change", this, false);
}

DataBind.prototype.handleEvent = function(event) {
    switch (event.type) {
        case "change": this.change(this.element.value);
    }
};

DataBind.prototype.change = function(value) {
    this.data = value;
    this.element.value = value;
};

var obj = new DataBind(document.getElementById("foo"), "initial");

// simulate some JS based changes.
var i = 0;
setInterval(function() {
    obj.change(obj.element.value + ++i);
}, 3000);