函数中的getter和Setter（javascript） [英] Getters and Setters in a function (javascript)

问题描述

在像这样的对象中使用get时，get有效：

When using "get" in an object like this, "get" works:

    var people = {
      name: "Alex",
      get sayHi() {
        return `Hi, ${this.name}!`
        }
    };

var person = people;

document.write(person.sayHi);

但是使用函数我收到错误。如何在这样的函数中使用Getters和Setter？

But with a function I get an error. How to use Getters and Setters in a function like this?

function People2() {
  this.name = "Mike";
  get sayHi() {
    return `Hi, ${this.name}!`;
  }
};

var user = new People2();

document.write(user.sayHi);

推荐答案

您可以使用实际的获取和设置仅在类（ES2015）和对象文字中的关键字。

You can use the actual get and set keywords only in classes (ES2015) and object literals.

在ES5中，您通常会使用 Obect.defineProperty 来实现你想要实现：

In ES5, your would typically use Obect.defineProperty to implement what you're trying to achieve:

function People2() {
    this.name = "Mike";
}
Object.defineProperty(People2.prototype, "sayHi", {
    get: function() {
        return "Hi, " + this.name + "!";
    }
});

ECMAScript 2015

在ES2015中，你也可以使用类来实现所需的行为：

ECMAScript 2015

In ES2015, you could also use classes to achieve the desired behavior:

class People2 {
    constructor() {
        this.name = "Mike";
    }
    get sayHi() {
        return `Hi, ${this.name}!`;
    }
}

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