使用JavaScript中的对象文字实现继承

Question

How do i achieve this :

function Vehicle(){
    this.mobility = true;
};
function Car(){};
Car.prototype = new Vehicle();
var myCar = new Car();
console.log(myCar.mobility);

Using objects created with Object literals ?

I know about Object.create() but is there any way like

Car.prototype = new Vehicle();

to achieve that ?

Answer 1

Here's how you do it using __proto__ :

var propertiesToInherit = { 'horsepower': 201, 'make': 'Acura' }
var myCar = {};
myCar.__proto__ = propertiesToInherit;

console.log(myCar.horsepower); // 201
console.log(myCar.make); // Acura

That being said, I would avoid doing this. It looks like it is deprecated

Answer 2

One possibility would be Prototype.js ; among other things, it allows you to create and extend JS classes using a cleaner syntax:

// properties are directly passed to `create` method
var Person = Class.create({
  initialize: function(name) {
    this.name = name;
  },
  say: function(message) {
    return this.name + ': ' + message;
  }
});

// when subclassing, specify the class you want to inherit from
var Pirate = Class.create(Person, {
  // redefine the speak method
  say: function($super, message) {
    return $super(message) + ', yarr!';
  }
});

var john = new Pirate('Long John');
john.say('ahoy matey');
// -> "Long John: ahoy matey, yarr!"

Answer 3

I don't know if I understand your question correctly, but maybe you could try this:

var literal = { mobility: true };
function Car(){};
Car.prototype = literal;
var myCar = new Car();
console.log(myCar.mobility);

Note that if you change the literal, you change all instances of Car that were created.