Simulating traits on javascript

trait.js

'use strict'

var trait = {}

trait.whatever = function (context) {
    context.prototype.exec = function () {
        console.log(this.i)
    }
}

var A = function () {
    this.i = 'teste _ A'
}
trait.whatever(A)

var B = function () {
    this.i = 'teste _ B'
}
trait.whatever(B)

var a = new A();
var b = new B();

a.exec();
b.exec();