Some Date monkey patches, because I don't need to use `moment js` and javascript Date is as useful as airplane horn

date-monkey-patches.js

Date.prototype.advanceDays = function(days) {
  let d = new Date(this);
  return new Date(d.setDate(this.getDate() + days));
};
Date.prototype.beginningOfWeek = function() {
  return this.advanceDays((this.getDay() == 0 ? -6 : 1) - this.getDay());
};

Date.prototype.getWeekName = function() {
  return ['S', 'M', 'T', 'W', 'T', 'F', 'S'][this.getDay()];
};
Date.prototype.getMonthName = function() {
  return ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'][this.getMonth()];
};

Date.prototype.queryFormat = function() {
  return this.getFullYear() + '-' + (this.getMonth() + 1) + '-' + this.getDate();
};
Date.prototype.simpleFormat = function() {
  return this.getDate() + ' ' + this.getMonthName();
};