浅谈js中Object.create()与new的具体实现与区别

function A() {
    this.name = 'abc';
}
A.prototype.a = 'a';
A.prototype.showName = function () {
    return this.name;
}
var a1 = new A();
var a2 = Object.create(A.prototype);

Object.create =  function (o) {
    var F = function () {};
    F.prototype = o;
	return new F();
};

var newFunc = function ( func ){
    var obj = Object.creat(func.prototype);
    var ret = func.call(obj);
    if(typeof ret === 'object') { 
    	return ret;
     }
    else { 
    	return obj;
    }
}

a1.__proto__ == a2.__proto__；  // true
a1.__proto__ == A.prototype;  // true
a2.__proto__ == A.prototype;  // true
a1.__proto__.__proto__ == Object.prototype; // true
a1.__proto__.__proto__.__proto__ == null; // true

function Parent(name, age) {
   this.name = name;
     this.age = age;
}
Parent.prototype.showName = function () {
    return this.name;
}
function Child(name, age) {
    Parent.call(this, name, age);   // 这里调用一次父类构造函数
}
Child.prototype = new Parent();  // 这里也会调用父类构造函数
Child.prototype.constructor = Child;

function Parent(name, age) {
   this.name = name;
     this.age = age;
}
Parent.prototype.showName = function () {
    return this.name;
}
function Child(name, age) {
    Parent.call(this, name, age);   // 这里调用一次父类构造函数
}
Child.prototype = Object.create(Parent.prototype);  // 这里避免了调用父类构造函数
Child.prototype.constructor = Child;