<span style=”font-size:12px;”>var Animal = new Class({
initialize: function(age){
this.age = age;
}
});
var Cat = new Class({
Extends: Animal,
initialize: function(name, age){
this.parent(age); // calls initalize method of Animal class
this.name = name;
}
});
var myCat = new Cat(‘Micia’, 20);
console.log(myCat.name); //’Micia’.
console.log(myCat.age); // 20.</span>

<span style=”font-size:12px;”>var Dog = new Class({
Implements: Animal,
setName: function(name){
this.name = name
}
});
var myAnimal = new Dog(20);
console.log(myAnimal.age);
myAnimal.setName(‘Micia’);
console.log(myAnimal.name); // ‘Micia’.
</span>

通過Extends實現繼承時，需要通過調用parent方法來調用父元素的initialize方法從而繼承父元素的屬性

而通過Implements實現繼承時，直接就可以繼承父元素的屬性，這種方式很適合父類不止一個的情況下

另外額外補充類方法Implement和extend，這兩個方法用于擴展已經定義了的類

<span class=”kw2″><span style=”font-size:12px”></span></span><pre name=”code” class=”javascript”><span style=”font-size:12px;”>var Animal = new Class({
initialize: function(age){
this.age = age;
}
});
Animal.implement({
setName: function(name){
this.name = name;
}
});
var myAnimal = new Animal(20);
myAnimal.setName(‘Micia’);
console.log(myAnimal.name); //’Micia'</span></pre><span style=”font-size:12px”>
<span class=”co1″></span></span>

“The main difference between extend and implement is that Implement changes the class’s prototype, while Extend creates a copy. This means that if you implement a change into a class all instances of that class will inherit that change instantly, while if you use Extend then all existing instances will remain the same。”

簡單翻譯下:extend和implement的主要區別是，implement改變了類的prototype屬性，而extend只是新建了一個副本。這意味著如果你通過implement對類做了改變，那將改變他的所有實例，而通過extend改變類的話，不會改變在此之前存在的實例。

var Thingy = new Class({
go: function(){
alert(‘hi’);
}
});
var myClass = new Thingy();
myClass.go(); /* alerts ‘hi’ */
Thingy.implement({
go: function(){
alert(‘implemented’);
}
});
myClass.go(); /* alerts ‘implemented’ */
Thingy = Thingy.extend({
go: function(){
alert(‘extended’);
}