MyClass.operator.lookup(index)
{
     return myArray[index];
}

MyClass = function(){
    // Set some defaults that belong to the class via dot syntax or array syntax.
    this.some_property = 'my value is a string';
    this['another_property'] = 'i am also a string';
    this[0] = 1;
};

foo = new MyClass();
foo.some_property;  // Returns 'my value is a string'
foo['some_property'];  // Returns 'my value is a string'
foo.another_property;  // Returns  'i am also a string'
foo['another_property'];  // Also returns 'i am also a string'
foo.0;  // Syntax Error
foo[0];  // Returns 1
foo['0'];  // Returns 1

MyClass.operator.lookup(index)
{
    get { return myArray[index]; }
    set { myArray[index] = value; }
}