下面的例子演示了如何使用Object.create()来实现类式继承。这是一个所有版本JavaScript都支持的单继承。
// Shape - superclass
function Shape() {
this.x = 0;
this.y = 0;
}
// superclass method
Shape.prototype.move = function(x, y) {
this.x += x;
this.y += y;
console.info('Shape moved.');
};
// Rectangle - subclass
function Rectangle() {
Shape.call(this); // call super constructor.
}
// subclass extends superclass
Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;
var rect = new Rectangle();
console.log('Is rect an instance of Rectangle?',
rect instanceof Rectangle); // true
console.log('Is rect an instance of Shape?',
rect instanceof Shape); // true
rect.move(1, 1); // Outputs, 'Shape moved.'
如果你希望能继承到多个对象，则可以使用混入的方式。
function MyClass() {
SuperClass.call(this);
OtherSuperClass.call(this);
}
// inherit one class
MyClass.prototype = Object.create(SuperClass.prototype);
// mixin another
Object.assign(MyClass.prototype, OtherSuperClass.prototype);
// re-assign constructor
MyClass.prototype.constructor = MyClass;
MyClass.prototype.myMethod = function() {
// do a thing
};
转自MDN
