date-fns, days of month

index.js

const df = require('date-fns');

const today = Date.now();
const tomorrow = df.addDays(today, 1);

function getWorkDaysInMonth(day) {
  return df.eachDay(df.startOfMonth(day), df.endOfMonth(day))
    .filter(date => !df.isWeekend(date))
    .map(date => df.format(date, 'ddd Do'));
}

console.log(getWorkDaysInMonth(today).length);
console.log(getWorkDaysInMonth(tomorrow).length);

/*
$('.btn-link[type="button"]')[0].click();
$('textarea[placeholder="Type or click to select an item."]')[0].click()
$('.ac-option.active a').click()
$('textarea.item-description[name="Consultancy"]')[0].value = "XXX date";
*/

package.json

{
  "name": "try-month",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "date-fns": "^1.29.0"
  }
}