NodeJS 中的 JavaScript OOP：如何？

javascript oop node.js inheritance mongoose

2022-08-30 04:55:51

我习惯了Java中的经典OOP。

使用 NodeJS 在 JavaScript 中执行 OOP 的最佳实践是什么？

每个类都是一个带有？module.export

如何创建类？

this.Class = function() {
    //constructor?
    var privateField = ""
    this.publicField = ""
    var privateMethod = function() {}
    this.publicMethod = function() {} 
}

vs. （我甚至不确定它是否正确）

this.Class = {
    privateField: ""
    , privateMethod: function() {}

    , return {
        publicField: ""
        publicMethod: function() {}
    }
}

与。

this.Class = function() {}

this.Class.prototype.method = function(){}

...

继承如何运作？

是否有用于在 NodeJS 中实现 OOP 的特定模块？

我正在寻找一千种不同的方法来创建类似于OOP的东西。但我不知道什么是最常用/实用/干净的方式。

奖励问题：建议与MongooseJS一起使用的“OOP风格”是什么？（是否可以将 MongooseJS 文档视为类，并将模型用作实例？

编辑

这是JsFiddle中的一个例子，请提供反馈。

//http://javascriptissexy.com/oop-in-javascript-what-you-need-to-know/
function inheritPrototype(childObject, parentObject) {
    var copyOfParent = Object.create(parentObject.prototype)
    copyOfParent.constructor = childObject
    childObject.prototype = copyOfParent
}

//example
function Canvas (id) {
    this.id = id
    this.shapes = {} //instead of array?
    console.log("Canvas constructor called "+id)
}
Canvas.prototype = {
    constructor: Canvas
    , getId: function() {
        return this.id
    }
    , getShape: function(shapeId) {
        return this.shapes[shapeId]
    }
    , getShapes: function() {
        return this.shapes
    }
    , addShape: function (shape)  {
        this.shapes[shape.getId()] = shape
    }
    , removeShape: function (shapeId)  {
        var shape = this.shapes[shapeId]
        if (shape)
            delete this.shapes[shapeId]
        return shape
    }
}

function Shape(id) {
    this.id = id
    this.size = { width: 0, height: 0 }
    console.log("Shape constructor called "+id)
}
Shape.prototype = {
    constructor: Shape
    , getId: function() {
        return this.id
    }
    , getSize: function() {
        return this.size
    }
    , setSize: function (size)  {
        this.size = size
    }
}

//inheritance
function Square(id, otherSuff) {
    Shape.call(this, id) //same as Shape.prototype.constructor.apply( this, arguments ); ?
    this.stuff = otherSuff
    console.log("Square constructor called "+id)
}
inheritPrototype(Square, Shape)
Square.prototype.getSize = function() { //override
    return this.size.width
}

function ComplexShape(id) {
    Shape.call(this, id)
    this.frame = null
    console.log("ComplexShape constructor called "+id)
}
inheritPrototype(ComplexShape, Shape)
ComplexShape.prototype.getFrame = function() {
    return this.frame
}
ComplexShape.prototype.setFrame = function(frame) {
    this.frame = frame
}

function Frame(id) {
    this.id = id
    this.length = 0
}
Frame.prototype = {
    constructor: Frame
    , getId: function() {
        return this.id
    }
    , getLength: function() {
        return this.length
    }
    , setLength: function (length)  {
        this.length = length
    }
}

/////run
var aCanvas = new Canvas("c1")
var anotherCanvas = new Canvas("c2")
console.log("aCanvas: "+ aCanvas.getId())

var aSquare = new Square("s1", {})
aSquare.setSize({ width: 100, height: 100})
console.log("square overridden size: "+aSquare.getSize())

var aComplexShape = new ComplexShape("supercomplex")
var aFrame = new Frame("f1")
aComplexShape.setFrame(aFrame)
console.log(aComplexShape.getFrame())

aCanvas.addShape(aSquare)
aCanvas.addShape(aComplexShape)
console.log("Shapes in aCanvas: "+Object.keys(aCanvas.getShapes()).length)

anotherCanvas.addShape(aCanvas.removeShape("supercomplex"))
console.log("Shapes in aCanvas: "+Object.keys(aCanvas.getShapes()).length)
console.log("Shapes in anotherCanvas: "+Object.keys(anotherCanvas.getShapes()).length)

console.log(aSquare instanceof Shape)
console.log(aComplexShape instanceof Shape)

答案 1

这是一个开箱即用的示例。如果你想要更少的“hacky”，你应该使用继承库等。

好吧，在文件动物中.js你会这样写：

var method = Animal.prototype;

function Animal(age) {
    this._age = age;
}

method.getAge = function() {
    return this._age;
};

module.exports = Animal;

要在其他文件中使用它：

var Animal = require("./animal.js");

var john = new Animal(3);

如果你想要一个“子类”，那么在鼠标内部.js：

var _super = require("./animal.js").prototype,
    method = Mouse.prototype = Object.create( _super );

method.constructor = Mouse;

function Mouse() {
    _super.constructor.apply( this, arguments );
}
//Pointless override to show super calls
//note that for performance (e.g. inlining the below is impossible)
//you should do
//method.$getAge = _super.getAge;
//and then use this.$getAge() instead of super()
method.getAge = function() {
    return _super.getAge.call(this);
};

module.exports = Mouse;

您也可以考虑“方法借用”而不是垂直继承。您无需从“类”继承即可在类上使用其方法。例如：

 var method = List.prototype;
 function List() {

 }

 method.add = Array.prototype.push;

 ...

 var a = new List();
 a.add(3);
 console.log(a[0]) //3;

答案 2

作为 Node.js社区确保将 JavaScript ECMA-262 规范中的新功能及时引入 Node.js开发人员。

你可以看看JavaScript类。MDN链接到JS类在 ECMAScript 6 中引入了 JavaScript 类，此方法提供了在 Javascript 中对 OOP 概念进行建模的更简单方法。

注意：JS类只能在严格模式下工作。

下面是一些类的骨架，继承写在Node.js（Used Node.js Version v5.0.0 )

类声明：

'use strict'; 
class Animal{

 constructor(name){
    this.name = name ;
 }

 print(){
    console.log('Name is :'+ this.name);
 }
}

var a1 = new Animal('Dog');

遗产：

'use strict';
class Base{

 constructor(){
 }
 // methods definitions go here
}

class Child extends Base{
 // methods definitions go here
 print(){ 
 }
}

var childObj = new Child();