js 手写new

1. 创建一个新对象base，将base的原型链设置为构造函数的原型
2. new构造函数，构造函数的this指向新对象，可以为新对象添加实例属性
3. 执行构造函数，如果构造函数自己有引用类型的返回值ret，就用ret, 否则用base

    const isValidRet = v => v !== null && (typeof v === "object" || typeof v === "function")
    const objectFactory = function (Ctor, ...args) {
        if (typeof Ctor !== 'function') throw 'Ctor must be a function'
        const base = Object.create(Ctor.prototype)
        const ret = Ctor.apply(base, args)
        return isValidRet(ret) ? ret : base
    }

    
    const F = function (a, b) {
        this.a = a
        this.b = b
        return null
    }
    console.dir(objectFactory(F, 1, 2));
    console.dir(objectFactory());