1，创建一个空对象
2，链接到构造函数的原型
3，绑定this到该对象
4，返回新对象

function newF(FN, ...args) {
    var obj = {}
    obj.__proto__ = FN.prototype
    var result = FN.apply(obj, args)
    return typeof result === "object" ? result : obj
}

function Person(name, age) {
    this.name = name
    this.age = age
}

var p = newF(Person, "bobo", 23)
console.log(p)

console.log(p instanceof Person)

使用Object.create简化写法

function newF(FN, ...args) {
    var obj = Object.create(FN.prototype)
    var result = FN.apply(obj, args)
    return typeof result === "object" ? result : obj
}