ES6 Proxy Optional Chain

optional.js

const optional = (srcObj) => {
  return new Proxy(() => {}, {
    apply: () => {
      return srcObj
    },
    get: (__, prop) => {
      if (srcObj && srcObj.hasOwnProperty(prop)) {
        return optional(srcObj[prop])
      } else {
        return optional(undefined)
      }
    },
  })
}

const obj = {
  a: 1,
  b: { c: 'c', d: null },
}

console.log(optional(obj)())
console.log(optional(obj).b.c())
console.log(optional(obj).b.d())
console.log(optional(obj).b.d.e())