util.inherits(constructor, superConstructor)
extends
关键字。constructor
<Function>superConstructor
<Function>
不鼓励使用 util.inherits()
。
请使用 ES6 class
和 extends
关键字来获得语言级别的继承支持。
另请注意,这两种风格在语义上不兼容。
将原型方法从一个构造函数继承到另一个构造函数。
constructor
的原型将被设置为从 superConstructor
创建的新对象。
这主要是在 Object.setPrototypeOf(constructor.prototype, superConstructor.prototype)
之上添加了一些输入验证。
作为额外的便利,superConstructor
将可通过 constructor.super_
属性访问。
const util = require('node:util');
const EventEmitter = require('node:events');
function MyStream() {
EventEmitter.call(this);
}
util.inherits(MyStream, EventEmitter);
MyStream.prototype.write = function(data) {
this.emit('data', data);
};
const stream = new MyStream();
console.log(stream instanceof EventEmitter); // true
console.log(MyStream.super_ === EventEmitter); // true
stream.on('data', (data) => {
console.log(`Received data: "${data}"`);
});
stream.write('It works!'); // 接收到的数据:"It works!"
使用 class
和 extends
的 ES6 示例:
const EventEmitter = require('node:events');
class MyStream extends EventEmitter {
write(data) {
this.emit('data', data);
}
}
const stream = new MyStream();
stream.on('data', (data) => {
console.log(`Received data: "${data}"`);
});
stream.write('With ES6');
extends
keyword instead.constructor
<Function>superConstructor
<Function>
Usage of util.inherits()
is discouraged. Please use the ES6 class
and
extends
keywords to get language level inheritance support. Also note
that the two styles are semantically incompatible.
Inherit the prototype methods from one constructor into another. The
prototype of constructor
will be set to a new object created from
superConstructor
.
This mainly adds some input validation on top of
Object.setPrototypeOf(constructor.prototype, superConstructor.prototype)
.
As an additional convenience, superConstructor
will be accessible
through the constructor.super_
property.
const util = require('node:util');
const EventEmitter = require('node:events');
function MyStream() {
EventEmitter.call(this);
}
util.inherits(MyStream, EventEmitter);
MyStream.prototype.write = function(data) {
this.emit('data', data);
};
const stream = new MyStream();
console.log(stream instanceof EventEmitter); // true
console.log(MyStream.super_ === EventEmitter); // true
stream.on('data', (data) => {
console.log(`Received data: "${data}"`);
});
stream.write('It works!'); // Received data: "It works!"
ES6 example using class
and extends
:
const EventEmitter = require('node:events');
class MyStream extends EventEmitter {
write(data) {
this.emit('data', data);
}
}
const stream = new MyStream();
stream.on('data', (data) => {
console.log(`Received data: "${data}"`);
});
stream.write('With ES6');