javascript - 有没有办法发现 javascript 6 类是否定义了自己的构造函数？

Question

有什么方法可以确定子类是否从静态方法(基类中)实现构造函数？

我正在尝试编写一个静态 create 方法(其作用类似于 new 关键字)，默认情况下通过将属性值作为属性对象传递来工作:

class Person extends Class {
    greet() { return 'hello from ' + this.name; }
}
var p = Person.create({name: 'world'};  // create a new Person object and set its `name` property to `'world'`
console.log(p.greet());  // => "hello from world"

但是将其交给类的构造函数(如果有的话):

class Person2 extends Class {
    constructor(name) {
        super();
        this.name = name;
    }
    greet() { return 'hello from ' + this.name; }
}
var p = Person2.create('world');
console.log(p.greet());  // => "hello from world"

我一直在寻找子类是否定义了自己的构造函数......

class Class {
    static create(...args) {
        let has_ctor = ??  // true iff the current subclass defines a constructor..

        if (has_ctor) {
            // let the constructor handle everything
            return new this(...args);
        } else {
            // assume that `args` contains exactly 1 pojo that defines instance variables to be overridden..
            var instance = new this();
            let props = args[0];
            for (let prop in props) instance[prop] = props[prop];
            return instance;
        }
    }
}

这可能吗？

Answer 1

看起来会更容易做到

class Class {
    static create(...args) {
        // let the constructor handle everything
        return new this(...args);
    }
    constructor(props){
        Object.assign(this, props);
    }
}

然后，如果事物覆盖构造函数，则可以选择将 Prop 传递给 super() 或自行手动分配它们。