daysuntil.js

// daysuntil.js
// (C) 2012+ by Steakscorp Labs and Jinhai Steakhouse

// Calculates the number of days between two dates, or
// the number of days between today and some date in
// the future

// Number of milliseconds per day
const ONE_DAY = 86400000;
const MONTHS = ["January", "February", "March", "April", "May",
	"June", "July", "August", "September", "October", 
	"November", "December"]
// If no parser string, default to this one
const defaultDateString = "from=xxxxxxxx&to=11082015"

function runAll() {
// Parses URL, determines date, determines length between dates
// and finally posts it on the webpage
	var dates = formatMyan(parseURL());
	var dateArray = converterMyan(dates);
	var daysCount = daysUntil(dateArray[0], dateArray[1]);
	webPost(daysCount, dateTranslate(dateArray[1]));
}

function parseURL() {
// Parses URL
	var parser = document.createElement('a');
	parser.href = document.URL;
	if (parser.search == "") {
		parser.search = defaultDateString;
	}

	return parser.search;
}

function formatMyan(str) {
// Parses search string and returns an array of dates
	var elementOne = str.split('&')[0].substr(6);
	var elementTwo = str.split('&')[1].substr(3);
	var formatArray = [elementOne, elementTwo];
	return formatArray;
}

function converterMyan(dateArray) {
// Takes in an string array and returns an array of dates
	var finalArray = new Array();
	
	if (dateArray[0] == "xxxxxxxx") {
		finalArray[0] = new Date();
		// Below: get Date in current timezone
		//finalArray[0] = new Date(getFullYear(), getMonth(), 
		//	getDate(), getHours(), getMinutes(), 
		//	getSeconds(), getMilliseconds());
	}

	else {
		finalArray[0] = new Date(
			parseInt(dateArray[0].substr(4,8)), 
			parseInt(dateArray[0].substr(0,2)) - 1,
			parseInt(dateArray[0].substr(2,2)));
	}

	finalArray[1] = new Date(
		parseInt(dateArray[1].substr(4,8)),
                parseInt(dateArray[1].substr(0,2)) - 1,
                parseInt(dateArray[1].substr(2,2)));
	
	return finalArray;
}

function daysUntil(date1, date2) {
	// Conversion of both dates to milliseconds
	var date1_ms = date1.getTime();
	var date2_ms = date2.getTime();
	var difference;

	if (date1_ms < date2_ms) {
		// Calculate difference
		difference = Math.abs(date1_ms - date2_ms);
	}

	else {
		difference = 0;
	}

	// Now convert to days
	return Math.round(difference/ONE_DAY);
}

function dateTranslate(date) {
// Translates a number date into a full text date
	var month = MONTHS[date.getMonth()];
	var day = date.getDate();
	var year = date.getFullYear();
	
	// Put it together
	var textDate = month + " " + day + ", " + year;
	return textDate;
}

function webPost(text, text2) {
// Finally, post it to the webpage
	document.getElementById('daysuntil').innerHTML = text;
	document.getElementById('enddate').innerHTML = text2;
}