js面向对象编程，定义类的四种方法

/* Anim class. */

var Anim = function() {
...
};
Anim.prototype.start = function() {
...
};
Anim.prototype.stop = function() {
...
};

/* Usage. */

var myAnim = new Anim();
myAnim.start();
...
myAnim.stop();

/* Anim class, with a slightly different syntax for declaring methods. */

var Anim = function() {
...
};
Anim.prototype = {
start: function() {
...
},
stop: function() {
...
}
};

/* Add a method to the Function class that can be used to declare methods. */

Function.prototype.method = function(name, fn) {
this.prototype[name] = fn;
};

/* Anim class, with methods created using a convenience method. */

var Anim = function() {
...
};
Anim.method('start', function() {
...
});
Anim.method('stop', function() {
...
});

/* This version allows the calls to be chained. */

Function.prototype.method = function(name, fn) {
this.prototype[name] = fn;
return this;
};

/* Anim class, with methods created using a convenience method and chaining. */

var Anim = function() {
...
};
Anim.
method('start', function() {
...
}).
method('stop', function() {
...
});