javascript - 使用“ Object.create”代替“ new”(Using “Object.create” instead of “new”)

Question

Javascript 1.9.3 / ECMAScript 5 introduces Object.create , which Douglas Crockford amongst others has been advocating for a long time.(Javascript 1.9.3 / ECMAScript 5引入了Object.create ，这是Douglas Crockford等人提倡的很长时间了。)

How do I replace new in the code below with Object.create ?(如何使用Object.create替换下面代码中的new ？) var UserA = function(nameParam) { this.id = MY_GLOBAL.nextId(); this.name = nameParam; } UserA.prototype.sayHello = function() { console.log('Hello '+ this.name); } var bob = new UserA('bob'); bob.sayHello(); (Assume MY_GLOBAL.nextId exists).(（假设存在MY_GLOBAL.nextId ）。) The best I can come up with is:(我能想到的最好的是：) var userB = { init: function(nameParam) { this.id = MY_GLOBAL.nextId(); this.name = nameParam; }, sayHello: function() { console.log('Hello '+ this.name); } }; var bob = Object.create(userB); bob.init('Bob'); bob.sayHello(); There doesn't seem to be any advantage, so I think I'm not getting it.(似乎没有任何优势，所以我想我没有。) I'm probably being too neo-classical.(我可能太新古典了。) How should I use Object.create to create user 'bob'?(我应该如何使用Object.create创建用户“ bob”？)   ask by Graham King translate from so

Answer 1

With only one level of inheritance, your example may not let you see the real benefits of Object.create .(仅具有一个继承级别，您的示例可能无法让您看到Object.create的真正好处。)

This methods allows you to easily implement differential inheritance , where objects can directly inherit from other objects.(通过此方法，您可以轻松实现差异继承 ，其中对象可以直接从其他对象继承。) On your userB example, I don't think that your init method should be public or even exist, if you call again this method on an existing object instance, the id and name properties will change.(在您的userB示例中，我认为您的init方法不应该是公共的，甚至不存在，如果您在现有对象实例上再次调用此方法，则id和name属性将发生变化。) Object.create lets you initialize object properties using its second argument, eg:(Object.create允许您使用第二个参数来初始化对象属性，例如：) var userB = { sayHello: function() { console.log('Hello '+ this.name); } }; var bob = Object.create(userB, { 'id' : { value: MY_GLOBAL.nextId(), enumerable:true // writable:false, configurable(deletable):false by default }, 'name': { value: 'Bob', enumerable: true } }); As you can see, the properties can be initialized on the second argument of Object.create , with an object literal using a syntax similar to the used by the Object.defineProperties and Object.defineProperty methods.(正如可以看到，该属性可以被上的第二个参数进行初始化Object.create字面使用类似于由所使用的语法，与对象Object.defineProperties和Object.defineProperty方法。) It lets you set the property attributes ( enumerable , writable , or configurable ), which can be really useful.(它使您可以设置属性属性（ enumerable ， writable或configurable ），这很有用。)