Use Date.prototype.getDay() to check weekend by using a modulo operator (%).
Time & Date
How to Add and Subtract Time From a Date in JavaScript
How you can add time to a Date object and subtract time from a Date object in JavaScript.
Get a formatted list of months
Here’s a trick for getting back a formatted month name (like January or Jan).
Get the date for a specific day of the week
Here’s a way to get the date for the next occurrence of a specific day of the week.
Check if a date is after another date
Use the greater than operator (>) to check if the first date comes after the second one.
Check if a date is before another date
Use the less than operator (<) to check if the first date comes before the second one.
Check if a date is between two other dates
Use the greater than (>) and less than (<) operators to check if date is between dateStart and dateEnd.
Get the amount of time from now for a date
Here is a vanilla JS alternative to the moment.js timeFromNow() method.
Alarm Clock
Set an alarm that will play any sound from your computer. You can even select a snooze time after it sounds. Awesome!
Simple Calendar
This script displays a calendar page of the chosen month and year. The function takes a date object as its parameter. If it is omitted, the calendar will default to the date on the client computer.