详解JavaScript中new操作符的解析和实现

function new_ (constr, ...rests) {
 var obj = {};
 obj.__proto__ = constr.prototype;
 var ret = constr.apply(obj, rests);
 return isPrimitive(ret) ? obj : ret; //判断构造函数的返回值是否为对象，不是则直接返回创建的obj对象
}

function new_(constr, ...rests) {
 if (typeof constr !== "function") {
 throw "the first param must be a function";
 }
 new_.target = constr;
 var obj = Object.create(constr.prototype);
 var ret = constr.apply(obj, rests);
 var isObj = typeof ret !== null && typeof ret === "object";
 var isFun = typeof ret === "function";
 //var isObj = typeof ret === "function" || typeof ret === "object" && !!ret;
 if (isObj || isFun) {
 return ret;
 }
 return obj;
}

function Person(name, age) {
 this.name = name;
 this.age = age;
}
Person.prototype.say = function () {
 console.log(this.name);
};
var p1 = new_(Person, 'clloz', '28')
var p2 = new_(Person, 'csx', '31')
console.log(p1); //Person {name: "clloz", age: "28"}
p1.say(); //clloz
console.log(p2); //Person {name: "csx", age: "31"}
p2.say(); //csx

console.log(p1.__proto__ === Person.prototype); //true
console.log(p2.__proto__ === Person.prototype); //true

Function.prototype.construct = function (aArgs) {
 var oNew = Object.create(this.prototype);
 this.apply(oNew, aArgs);
 return oNew;
};

function Clloz(...arguments) {
 if (!(this instanceof Clloz)) {
 return new Clloz(...arguments)
 }
}