__proto__ && prototypeide
一个对象的__proto__ 属性和本身的内部属性[[Prototype]]指向一个相同的值 (一般称这个值为原型)，原型的值能够是一个对象值也能够是null(好比说Object.prototype.__proto__的值就是null)。该属性可能会引起一些错误，由于用户可能会不知道该属性的特殊性,而给它赋值，从而改变了这个对象的原型。若是须要访问一个对象的原型，应该使用方法Object.getPrototypeOf。函数
当一个对象被建立时,它的 __proto__ 属性和内部属性[[Prototype]]指向了相同的对象 (也就是它的构造函数的prototype属性)。改变__proto__ 属性的值同时也会改变内部属性[[Prototype]]的值,除非该对象是不可扩展的。.net
什么是内部属性：http://my.oschina.net/xinxingegeya/blog/290167prototype
Be aware that __proto__ is not the same as prototype, since __proto__is a property of the instances (objects), whereas prototype is a property of the constructor functions used to create those objects. code
Consider another object called monkey and use it as a prototype when creating objects with the Human() constructor.对象
var monkey = {
feeds: 'bananas',
breathes: 'air'
};
function Human() {
}
Human.prototype = monkey;////使用monkey对象重写Human的prototype属性
var developer = new Human();
developer.feeds = 'pizza';
developer.hacks = 'JavaScript';
console.log(developer.hacks);//JavaScript
console.log(developer.feeds);//pizza
console.log(developer.breathes); //air
console.log(developer.__proto__ === monkey); //true
console.log(typeof developer.__proto__); //object
console.log(typeof developer.prototype);//undefined
console.log(typeof developer.constructor.prototype);//object
console.log(typeof developer.constructor); //function
The secret link is exposed in most modern JavaScript environments as the __proto__ property (the word "proto" with two underscores before and two after).blog
Be aware that __proto__is not the same as prototype, since __proto__is a property of the instances (objects), whereas prototype is a property of the constructor functions used to create those objects.ip
=======END=======underscore