Improve INTST 235 class calendar

intst235-calendar-improved.user.js

// ==UserScript==
// @name         INTST 235 Calendar Improved
// @namespace    https://gist.github.com/notyal/7d54b74e537183fa9a12ba27ff3cb2d4
// @version      1.0
// @description  Scroll to next assignment based on current date.
// @author       Layton Nelson
// @match        https://dl.dropboxusercontent.com/s/q39fy232p8li9na/calendar_235_f16.html?dl=0
// @grant        none
// @downloadURL  https://gist.github.com/notyal/7d54b74e537183fa9a12ba27ff3cb2d4/raw/intst235-calendar-improved.user.js
// @updateURL    https://gist.github.com/notyal/7d54b74e537183fa9a12ba27ff3cb2d4/raw/intst235-calendar-improved.user.js
// ==/UserScript==

(function() {
	'use strict';

	// allow adding days to date function
	// from: http://stackoverflow.com/a/563442
	Date.prototype.addDays=function(d){return new Date(this.valueOf()+864E5*d);};

	// get current date
	// exploit week days, such that only valid class days will be used
	var days = ["M","M","W","W","F","F","M"];
	var months = ["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sept","Oct","Nov","Dec"];
	var d = new Date();

	var classDay = days[d.getDay()];
	var classMonth = months[d.getMonth()];
	var classDate = d.getDate();

	console.log("Pre-adjusted date is: '" + classDay + " " + classMonth + " " + classDate + "'.");

	// add 1 day to classDate if class day is not (1,3,5)
	// also compute new classMonth
	switch (d.getDay()) {
		case 0: case 2: case 4: case 6:
			var d1 = d.addDays(1);
			// classDay doesn't need to be computed, since it has already been hacked
			classMonth = months[d1.getMonth()];
			classDate = d1.getDate();
			break;
	}

	// search for next class date
	var calString = classDay + " " + classMonth + " " + classDate + ":";

	// modified from: http://stackoverflow.com/a/3813334
	var tags = document.getElementsByTagName("h2");
	var found;

	console.log("Looking for date: '"+calString+"' ...");

	for (var i = 0; i < tags.length; i++) {
		if (tags[i].textContent == calString) {
			found = tags[i];
			break;
		}
	}

	// scroll and highlight element if it was found
	if (found === undefined){
		console.log("Error: could not find date.");
	} else {
		// scroll to found date
		console.log("Scrolling to date.");
		found.scrollIntoView(true); // positions element to top of view

		// set background color to a light yellow
		found.style.backgroundColor = '#ffc';
	}
})();