测试一
function F() {
this.__proto__.b = 1
}
var fn1 = new F()
fn1.__proto__.b = 6
console.log('fn1第一次打印:fn1.prototype.b的值为' + fn1.__proto__.b); //6
console.log(fn1);//fn1.__proto__指向fn的prototype,最新的prototype的b得值为52行代码修改的b=1
console.log('F第一次打印:F.prototype.b的值为' + F.prototype.b); //6
let fn2 = new F()
console.log('fn1第二次打印:fn1.prototype.b的值为' + fn1.__proto__.b); //1
console.log(fn2);//fn2.__proto__指向fn的prototype,此时修改了fn的prototype的b,使b=1
console.log('F第二次打印:F.prototype.b的值为' + F.prototype.b); //1
测试二
var obj = {
a: 1
}
console.log(obj.a, obj);
var obj2 = obj
obj2.a = 2
console.log(obj.a,obj);