como usar o isWeekday no javascript es6

Results in a boolean representation of a specific date.

Pass the specific date object firstly. Use Date.getDay() to check weekday by using a modulo operator and then returning a boolean.

const isWeekday = (t = new Date()) => {
  return t.getDay() % 6 !== 0;
};

isWeekday(); // true (if current date is 2019-07-19)

Acesse a Referência original