html5 - Javascript Object print object value -

i'm trying value object , prit on screen no success...

http://jsfiddle.net/lbascg4v/5/

app.js // função construtora function keydown(e) {    this.faq = e.keycode;     alert(e.keycode) }  // prototype com os métodos keydown.prototype = {    printr: function() {       alert(this.faq);    } }  window.addeventlistener('keydown', keydown, true);  index.html <canvas id="canvas" width="300" height="300" style="border: 1px solid red"></canvas>  <script> teste = new keydown(); teste.print();  </script> 

when push key on canvas, want value of key , put in object, want print object , value.

the real answer question you don't need prototyping:

function keydown(){    // initialize properties    this.faq = 0;    this.update = function(e){        // set faq        this.faq = e.keycode;    }    this.print = function(){        // alert faq        alert(this.faq);    } } 

and then:

window.

test = new keydown(); addeventlistener('keydown', test.update, true); test.print(); // alert 0 

working jsfiddle