Functions for excluding specific dates and weekends from time calculations

date-functions.js

const MS_IN_DAY = 86400000;

// Pretend this is the start/end time for a phase
var startDate = new Date("01/24/1989 08:30:23"),
    endDate = new Date("01/31/1989 16:32:23"),

    // This will be provided by the API -- extracted from a Google Calendar/iCal feed
    daysOff = [
		new Date("01/26/1989"),
		new Date("01/27/1989")
    ];

// Resets time to 00:00:00 on a date
function stripTime(date) {
	return new Date(date.toDateString());
}

// Returns true for weekends (Sat/Sun)
function isWeekend(date) {
	var day = date.getDay();
	return day === 0 || day === 6;
}

// Returns true for Monday-Friday
function isWeekDay(date) {
	return !isWeekend(date);
}

// Returns an array of date objects for every day between startDate and endDate (inclusive)
function getDatesBetween(startDate, endDate) {
	var startDate = stripTime(startDate),
		endDate = stripTime(endDate),
		date = startDate,
		dates = [startDate];

	while (date < endDate) {
		date = new Date(date.getTime() + MS_IN_DAY);
		dates.push(date);
	}

	return dates;
}

// Strip the time component of a date object
console.log(
	'Stripping the time from a date object:\n',
	stripTime(startDate)
);

// Get an array of date objects for every day between two dates
console.log(getDatesBetween(startDate, endDate));

// Strip weekends
console.log(
	'Exclude weekends:\n',
	getDatesBetween(startDate, endDate)
	.filter(date => !isWeekend(date))
);

// Strip days off from school
console.log(
	'Exclude 1/26 and 1/27:\n',
	getDatesBetween(startDate, endDate)
	.filter(date => daysOff.indexOf(date) === -1)
);

// Strip days off from school and weekends
console.log('Exclude weekends and 1/26 and 1/27:\n',
	getDatesBetween(startDate, endDate)
	.filter(date => daysOff.indexOf(date) === -1)
	.filter(date => !isWeekend(date))
);

// Returns an integer for 
function sectionCodeToGrade(code) {
    var matches = code.match(/(\d+|K)-\d+/);
    if (!matches) {
    	throw new Error('Unable to extract grade from section code: ' + code);
    }
    return matches[1] === 'K' ? 0 : parseInt(matches[1], 10);
}

output.txt

 1989-01-24T05:00:00.000Z
[ 1989-01-24T05:00:00.000Z,
  1989-01-25T05:00:00.000Z,
  1989-01-26T05:00:00.000Z,
  1989-01-27T05:00:00.000Z,
  1989-01-28T05:00:00.000Z,
  1989-01-29T05:00:00.000Z,
  1989-01-30T05:00:00.000Z,
  1989-01-31T05:00:00.000Z ]
Exclude weekends:
 [ 1989-01-24T05:00:00.000Z,
  1989-01-25T05:00:00.000Z,
  1989-01-26T05:00:00.000Z,
  1989-01-27T05:00:00.000Z,
  1989-01-30T05:00:00.000Z,
  1989-01-31T05:00:00.000Z ]
Exclude 1/26 and 1/27:
 [ 1989-01-24T05:00:00.000Z,
  1989-01-25T05:00:00.000Z,
  1989-01-26T05:00:00.000Z,
  1989-01-27T05:00:00.000Z,
  1989-01-28T05:00:00.000Z,
  1989-01-29T05:00:00.000Z,
  1989-01-30T05:00:00.000Z,
  1989-01-31T05:00:00.000Z ]
Exclude weekends and 1/26 and 1/27:
 [ 1989-01-24T05:00:00.000Z,
  1989-01-25T05:00:00.000Z,
  1989-01-26T05:00:00.000Z,
  1989-01-27T05:00:00.000Z,
  1989-01-30T05:00:00.000Z,
  1989-01-31T05:00:00.000Z ]