mapper object key in javascript

mapper.js

/*
 FUNCTION DESIGN

 Requirement:
 - not change source object

 Features:
 - mapping
 - include/exclude

 APIs:
 let mapped = mapper(src).map().ignoreAll().done()   // select mapped keys only
 let mapped = mapper(src).map().select().done()      // select mapped keys & some key
 let mapped = mapper(src).map().done()               // select mapped keys & all other keys
*/

// function style
function mapper(src = {}) {
  let _src = { ...src }
  let dest = {}
  return {
    map: function map(from, to) {
      dest[to] = _src[from]
      delete _src[from]
      return this
    },
    select: function select(...keys) {
      for (let k of keys) { dest[k] = _src[k] }
      _src = {}
      return this
    },
    ignore: function ignore(...keys) {
      for (let k of keys) {
        delete _src[k]
      }
      return this
    },
    ignoreAll: function ignoreAll() {
      _src = {}
      return this
    },
    done: function done() {
      return { ...dest, ..._src }
    }
  }
}

// class style
class Mapper {
  #dest = {}
  #_src
  constructor(src) {
    this.#_src = src
  }
  map(from, to) {
    this.#dest[to] = this.#_src[from]
    delete this.#_src[from]
    return this
  }
  select(...keys) {
    for (let k of keys) { this.#dest[k] = this.#_src[k] }
    this.#_src = {}
    return this
  }
  ignore(...keys) {
    for (let k of keys) {
      delete this.#_src[k]
    }
    return this
  }
  ignoreAll() {
    this.#_src = {}
    return this
  }
  done() {
    return { ...this.#dest, ...this.#_src }
  }

}


let src = { id: "abc", pwd: "xyz", name: "hello", age: 100, abc: "xxx", xyz: "xxx" }

let mappedF = mapper(src)
  .map("id", "Id")
  .map("pwd", "password")
  .ignore("name", "age")
  .done()

let mappedC = new Mapper(src)
  .map("id", "Id")
  .map("pwd", "password")
  .ignore("name", "age")
  .done()

console.log(mappedF)
console.log(mappedC)