javascript - JS 中的扩展属性？

Question

我们可以在 JavaScript 中将属性与对象在运行时关联起来吗就像我们在 C# 中所做的那样。 就像

class abc
{
a =1;
b=2;
}

abc obj;

obj.a // is right
//but can we do 
obj.c //.......... by any mean

Answer 1

function abc(){
    this.a = 1;
    this.b = 2;
}
var obj = new abc();
var obj2 = new abc();
obj.c = "something"; // will affect only this instance
obj2.prototype.d = "something else"; // this will influence all abc instances
alert(obj.d);