basic-Class.js

(function(d){

    d.Timer = function(args){
        // summary: The constructor function. Anytime we `new` up a Timer,
        //      this function is called, passing anything passed.
        //
        // example:
        //  |   var x = new dojo.Timer({ a:b });
        //  |   x.a == b // true
        d.mixin(this, args);
    };
    
    // add default values and member function to the Timer prototype:
    d.extend(d.Timer, {

        // value: Int
        //      Some value
        value:10,
        
        add: function(val){
            // summary: Add some passed `val` to this value. 
            // returns: Ourself, to allow chaining. 
            this.value += val;
            return this; // dojo.Timer
        },
        
        show:function(){
            // summary: Display our value
            console.log(this.value);
        }
    });
    
    // note: use full `dojo` here in string form, d is local
    d.declare("dojo.TimerTwo", d.Timer, {
        // summary: A Sub-class of a Timer, providing an overridden
        //      `add` behavior.
        add: function(val){
            // summary: Add some passed `val` to this value 
            //      but also subtract half the value of `val`
            // returns: Ourself, to allow chaining. 
            this.inherited(arguments);
            this.value -= (val / 2);
            return this; // dojo.TimerTwo
        }
    });
    
    // tests:
    var ti = new d.Timer(), 
        tt = new d.TimerTwo(),
        ttt = new d.Timer({ value: 20 })
    ;
    
    ti.add(10).show(); // adds 10, shows 20
    tt.add(10).show(); // adds 10, then subtracts 5, shows 15
    ttt.add(1).show(); // adds 1 to default of 20, shows 21
    
})(dojo);