"Multiple inheritance" in Javascript

_usage.js

function Parent() {}
Parent.prototype.a = 'Foo'
Parent.prototype.aGetter = function() {
  return this.a
}

function Child() {
  inherit(this, Parent)
}

var junior = new Child()
var senior = new Parent()

junior.aGetter() // retuns 'Foo'
senior.a = 'Bar'

senior.aGetter() // returns 'Bar'
junior.aGetter() // retuns 'Foo'

inherit.js

function inherit(child, parent) {
  parent.call(child);

  Object.keys(parent.prototype).forEach(function(key) {
    var value = parent.prototype[key]

    if (typeof value === 'function') {
      child[key] = value.bind(child)
    } else {
      child[key] = value
    }
  })
}