Edit in JSFiddle

//http://www.jermywells.com

var Person = Class.create({
  initialize: function(name) {
    this.name = name;
  },
  say: function(message) {
    return this.name + ': ' + message;
  }
});
var jeremy = new Person('jeremy');
document.getElementById('myDiv').innerHTML = jeremy.say('hello');

<div id="myDiv"></div>