Object extension

proxy.js

const wrap = (object) => {
  return new Proxy(object, {
    get(target, property, receiver) {
      switch (property) {
        case 'store':
          return (...args) => {
            return Reflect.set(object, ...args)
          }
          break
        case 'fetch':
          return (...args) => {
            const [key, defaultValue] = args
            return Reflect.get(object, key) || defaultValue
          }
          break
        case 'map':
          return (...args) => {
            const [mapper] = args
            return Object.keys(object).map(key => {
              return mapper(key, object[key])
            })
          }
      }
    }
  })
}

```
const a = {foobar: 2}
const b = wrap(a)
b.store('lukaku', 9)
=> true
b.fetch('foobar')
=> 2
a
=> {foobar: 2, lukaku: 9}
```