如何在 node.js 模块中实现继承？
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How to implement inheritance in node.js modules?
提问by Yalamber
I am in process of writing nodejs app. It is based on expressjs. I am confused on doing inheritance in nodejs modules. What i am trying to do is create a model base class, let's say my_model.js.
我正在编写 nodejs 应用程序。它基于 expressjs。我对在 nodejs 模块中进行继承感到困惑。我想要做的是创建一个模型基类，比如说 my_model.js。
module.exports = function my_model(){
my_model.fromID = function(){
//do query here
}
}
Now i want to use those methods in my_model in my other model class. let's say user_model.js How do i inherit my_model in user_model?
现在我想在我的其他模型类的 my_model 中使用这些方法。假设 user_model.js 我如何在 user_model 中继承 my_model？
回答by fardjad
in base_model:
在 base_model 中：
function BaseModel() { /* ... */ }
BaseModel.prototype.fromID = function () { /* ... */ };
module.exports = BaseModel;
in user_model:
在用户模型中：
var BaseModel = require('relative/or/absolute/path/to/base_model');
function UserModel() {
UserModel.super_.apply(this, arguments);
}
UserModel.super_ = BaseModel;
UserModel.prototype = Object.create(BaseModel.prototype, {
constructor: {
value: UserModel,
enumerable: false
}
});
UserModel.prototype.yourFunction = function () { /* ... */ };
module.exports = UserModel;
Instead of using Object.create()directly, you can also use util.inherits, so your user_modelbecomes:
除了Object.create()直接使用，您还可以使用util.inherits，这样您user_model就变成了：
var BaseModel = require('relative/or/absolute/path/to/base_model'),
util = require('util');
function UserModel() {
BaseModel.apply(this, arguments);
}
util.inherits(UserModel, BaseModel);
UserModel.prototype.yourFunction = function () { /* ... */ };
module.exports = UserModel;
回答by cmac
With ES6 the usage of util.inherits()is discouraged in favor of ES6 classand extends
在 ES6中不鼓励使用util.inherits()以支持 ES6类和扩展
const EventEmitter = require('events');
class MyStream extends EventEmitter {
constructor() {
super();
}
write(data) {
this.emit('data', data);
}
}
const stream = new MyStream();
stream.on('data', (data) => {
console.log(`Received data: "${data}"`);
});
stream.write('With ES6');
回答by Ivan V.
Using utility.inheritscan also help you decouple the childfrom the parent.
使用utility.inherits还可以帮助你解耦child从parent。
Instead of calling the parentexplicitly, you can use super_to call the parent.
parent您可以使用super_来调用父对象，而不是显式调用 。
var BaseModel = require('relative/or/absolute/path/to/base_model'),
util = require('util');
function UserModel() {
this.super_.apply(this, arguments);
}
util.inherits(UserModel, BaseModel);
utility.inheritssource:
utility.inherits来源：
var inherits = function (ctor, superCtor) {
ctor.super_ = superCtor;
ctor.prototype = Object.create(superCtor.prototype, {
constructor: {
value: ctor,
enumerable: false
}
});
};
