与类和对象相关的 JavaScript 开销

发布于 2024-11-19 20:54:21 字数 806 浏览 3 评论 0原文

我想知道与创建新类而不是该类的新对象相关的开销是小还是大。我正在使用 dojo，但我将提供纯 JS 的示例。我将在启动时创建 10 到 100 个对象，我认为这不会是一个严重的问题，但我想涵盖所有基础。

案例 1：Javascript 对象

function Person(name){
  this.name = name;
}
var p1 = new Person('Caine');
var p2 = new Person('Seth');
var p3 = new Person('Abel');

与案例 2：Javascript 类

function Person1(){
  this.name = 'Caine';
}

function Person2(){
  this.name = 'Seth';
}

function Person3(){
  this.name = 'Abel';
}
var p1 = new Person1();
var p2 = new Person2();
var p3 = new Person3();

编辑：人们想知道为什么我会采取这种方法。我正在实现一个模块化程序，用户可以根据需要创建和/或加载对象，而不是拥有一个 Person/Shape/Text... 类并使用 50,000,000 个参数（姓名、年龄、性别、标签、字体、 x , y , w , h...) 我想创建一个包含所有值的类。这也将简化代码的编辑，因为我希望允许用户从浏览器中查看和修改代码。我对 OOP 并不陌生，我确实意识到这偏离了标准编程过程，所以请相信我知道我在做什么 =)

原文

I was wondering if the overhead associated with creating a new class instead of a new object of that class was small or large. I am using dojo, but I will provide versus examples for pure JS. I will be creating between 10 and 100 objects once at start up, I don't think this will be a serious issue, but I want to cover all my bases.

Case 1: Javascript object

function Person(name){
  this.name = name;
}
var p1 = new Person('Caine');
var p2 = new Person('Seth');
var p3 = new Person('Abel');

Versus Case 2: Javascript Classes

function Person1(){
  this.name = 'Caine';
}

function Person2(){
  this.name = 'Seth';
}

function Person3(){
  this.name = 'Abel';
}
var p1 = new Person1();
var p2 = new Person2();
var p3 = new Person3();

EDIT : people want to know why I would ever take this approach. I'm implementing a modular program where the user creates and/or loads objects as desired, and rather than having one Person/Shape/Text... class and calling it with 50,000,000 arguments (name, age, sex, label, font, x , y , w , h...) I want to create a single class with all the values. This will also simplify editing the code as I want to allow the user to view and modify the code from within the browser. I am not new to OOP, and I do realize this is a departure from standard programing procedure, so have a little faith in that i know what i am doing =)

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靖瑶 2024-11-26 20:54:21

并不是真正的类（JS 没有它们），但在第二个示例中你得到的是两个额外的构造函数。每个都必须有一个自己的附加 prototype 属性对象。

因此，就创建和存储对象而言，第二种方法的效率稍低。但是，如果您有大量 Person1 实例，则第二种方法可以通过将共享属性放在原型上而不是单独放在每个新实例上来节省（少量）空间：

function Person1() {}
Person1.prototype.name= 'Caine';

保存一个 String 实例每个 Person1 实例。

实际上，它不会产生任何实际差异，您应该编写代码封装的思想的最清晰表达。（我个人认为每个名字都有不同的类别是不寻常的......）

Not really classes as such (JS doesn't have 'em), but what you've got in the second example is two additional constructor functions. Each will necessarily have an additional prototype property object of its own.

So your second approach is marginally less efficient in terms of objects created and stored. If you had lots of instances of Person1, though, the second approach could save (a tiny amount of) space by putting the shared property on the prototype instead of separately on each new instance:

function Person1() {}
Person1.prototype.name= 'Caine';

saving one String instance per Person1 instance.

In reality it's not going to make any practical difference and you should write whichever is the cleanest expression of the idea your code encapsulates. (Personally I think it'd be unusual to have a different class for each first name...)

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