Object Map excercise

object-map-exercise.ts

// https://www.typescriptlang.org/play?ssl=20&ssc=1&pln=1&pc=1#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

const fromEntries = (iterable: any) => [...iterable].reduce((obj, [key, val]) => {
    obj[key] = val
    return obj
  }, {})

function objectMap<T>(
  theObject: T,
  keyMapper: (k: keyof T) => string,
  valueMapper: (k: T[keyof T]) => unknown,
) {
  return fromEntries(
    Object.entries(theObject).map(([k, v]) => [keyMapper(k as keyof T), valueMapper(v)]),
  );
};

const myObject = { a: 1, b: 2, c: 3 };
const newObject = objectMap(myObject, k => `key_prefix:${k}`, v => 1000 * v);

console.log({ myObject, newObject });

//
// Add to Object prototype
//
// Object.defineProperty(Object.prototype, "map", {
//   get: function () {
//     return (keyMapper, valueMapper) => objectMap(this, keyMapper, valueMapper);
//   },
//   configurable: true,
// });