autobind implementation - bind all prototype methods to instance

bind.js

function binder(instance) {
  for (var prop in instance) {
    if (typeof instance[prop] === 'function' && !instance.hasOwnProperty(prop)) {
      instance[prop] = instance[prop].bind(instance);
    }
  }
}

function binder2(instance, prototype) {
  Object.keys(prototype)
    .filter(prop => typeof prototype[prop] === 'function')
    .forEach(prop => instance[prop] = prototype[prop]);
}

// binder(a);
// binder2(a, A.prototype);
// console.log(Object.keys(a));