isWeekend

Checks if the given date is a weekend.

• Use Date.prototype.getDay() to check weekend by using a modulo operator (%).
• Omit the argument, d, to use the current date as default.

const isWeekend = (d = new Date()) => d.getDay() % 6 === 0;

isWeekend(); // 2018-10-19 (if current date is 2018-10-18)