extend_Set_prototype.js

// https://tc39.github.io/ecma262/#sec-set-constructor
const MyList = class MyList extends Set {}

MyList.fromArray = function (aray) {
  const list = new MyList()
  array.forEach((a) => list.add(a)
  return list
}

MyList.prototype.has = function (ele) {
  let result = false
  for (const i of this) {
    if (i.property === ele) {
      result = true
      break
    }
  }
  return result
}