pick принимать объект и произвольное количество строк, а возвращать будет новый объект с перечисленными полями

const obj = {}
pick(obj, 'field-1', 'field-2', ...'field-n');

const fruits = {
 apple: 2,
 orange: 4,
 banana: 3
};
console.log(pick(fruits, 'apple', 'banana')); // { apple: 2, banana: 3 }

const pick = (o, ...a) => a.reduce((x, b) => o[b] ? (x[b] = o[b], x) : x, {});

function pick(ob, ...keys) {
  return Object.fromEntries(
    Object.entries(ob).filter(([key]) => keys.includes(key))
  );
}

const pick = (o, ...a) => a.reduce((x, b) => o.hasOwnProperty(b) ? (x[b] = o[b], x) : x, {});

const fruits = {
    apple: null,
    orange: 4,
    banana: undefined
};
 
console.log(pick(fruits, 'apple', 'banana')); // {apple: null, banana: undefined}

const pick = (obj, ...fields) => {
    return Object.fromEntries(Object.entries(obj).filter(([key]) => fields.includes(key)));
};

const pick = (obj, ...fields) => {
  for (const [key, value] of Object.entries(obj)) {
    if (fields.includes(key)) {
      newObj[key] = value;
    }
  }
  return newObj;
};

const pick = (obj, ...fields) => {
  const newObj = {}; // Uncaught ReferenceError: newObj is not defined
  for (const [key, value] of Object.entries(obj)) {
    if (fields.includes(key)) {
      newObj[key] = value;
    }
  }
  return newObj;
};

Object.prototype.pick = function (...p) {
    let o = {};
    for(let s of p) s in this ? o[s] = this[s] : null;
    return o;
};
 
const fruits = {
    apple: null,
    orange: 4,
    banana: 3
};
 
console.log(fruits.pick('apple', 'banana'));

function pick(ob, ...keys) {
  return Object.assign(
    new Proxy(
      {},
      {
        set(ob, key, value) {
          if (keys.includes(key)) {
            ob[key] = value;
          }
          return true;
        }
      }
    ),
    ob
  );
}

const pick = (obj, ...fields) => {
  let newObj = {};
  for (const fieldsArrElement of fields) {
    if (fieldsArrElement in obj) {
      newObj[`${fieldsArrElement}`] = obj[fieldsArrElement];
    }
  }
  return newObj;
};