SOURCE

function Widget(width,height) {
  this.width = width || 50;
  this.height = height || 50;
  this.$elem = null;
}

Widget.prototype.render = function($where) {
  if(this.$elem) {
    this.$elem.css({
      width: this.width + "px",
      height: this.height + "px"
    }).appendTo($where);
  }
};

function Button(width,height,label) {
  Widget.call(this,width,height);
  this.label = label || "Default";
  this.$elem = $("<button>").text(this.label);
}

Button.prototype = Object.create(Widget.prototype);

Button.prototype.render = function($where) {
  Widget.prototype.render.call( this, $where );
  this.$elem.click( this.onClick.bind( this ));
};

Button.prototype.onClick = function(evt) {
  console.log( this.label + " clicked!" );
};

$( document ).ready( function() {
  var $body = $( document.body );
  var btn1 = new Button( 125, 30, "Hello");
  var btn2 = new Button( 150, 40, "World");
  
  btn1.render( $body );
  btn2.render( $body );
})