[Masking / Plucking - Omitting / Copying Keys / Values from an Object Literal into another Object Literal] #LoDash #JavaScript

mask.js

/**
 * mask values from an object (inverse of pluck).
 * @param {Object} [obj={}] - an Object, null and undefined return an empty obj literal.
 * @param {[String]} [keys=[]] - an array of keys to mask/remove from the object.
 * @return {Object}
 */
const mask = (obj = {}, keys = []) => Object.keys(obj).reduce((ac, key) => {
    ac[key] = (keys.some((p)=>(p===key))) ? void 0 : obj[key];
    return ac;
}, {});

pluck.js

/**
 * pluck values from an object.
 * @param {Object} [obj={}] - an Object, null and undefined return an empty obj literal.
 * @param {[String]} [keys=[]] - an array of keys to plunk from the object.
 * @return {Object}
 */
const pluck = (obj = {}, keys = []) => (keys || []).reduce((ac, key) => {
  // eslint-disable-next-line no-param-reassign
  ac[key] = (obj) ? obj[key] : undefined;
  return ac;
}, {});

describe('pluck', () => {
  test.each([
    ['it should return an empty obj literal when undefined is specified for the object', undefined, [], {}],
    ['it should return an empty obj literal when undefined is specified for the key', {}, undefined, {}],
    ['it should return an empty obj literal when null is specified for the object', null, [], {}],
    ['it should return an empty obj literal when null is specified for the key', {}, null, {}],
    ['it should return an empty obj literal when {} is specified for the object', {}, ['a'], {}],
    ['it should return an empty obj literal when an empty array is specified for the key', { a: 'hello' }, [], {}],
    ['it should work with keys that have hyphens', { 'hello-world': true, 'omitted-key': false }, ['hello-world'], { 'hello-world': true }],
    ['it should work with a pure JSON-able object', { a: true, b: false }, ['a'], { a: true }],
  ])('%s', (
    testname, obj, keys, expectedResult,
  ) => {
    expect.assertions(1);
    expect(pluck(obj, keys)).toMatchObject(expectedResult);
  });
  test('it should work with a object that has a function',()=>{
    const obj = { a: function a() { console.log('yes'); }, b: false };
    expect(pluck(obj, ['a'])).toHaveProperty('a');
    expect(pluck(obj, ['a'])).not.toHaveProperty('b');
  });
});