Date.md

Date

Create today's Date

const now = new Date(); 
console.log(now); // 2020-10-11T11:26:42.835Z - time is offset from UTC 

Creating a custom Date

const swiftLaunch = new Date(2014, 8, 8); // year, month, day
console.log(swiftLaunch); // 2014-09-08T00:00:00.000Z

Using setMonth() and setDate()

const commencementDate = new Date(); 
commencementDate.setMonth(9); // months start from 0 
commencementDate.setDate(12); 

console.log(commencementDate); // 2020-10-12T11:36:04.975Z

Using getDay()

console.log(`Commencement in on a ${commencementDate.getDay()}`); // 1 is Monday

Challenges

Challenge 1

Write a JavaScript function to get the number of days in a month.

Test Data :

console.log(getDaysInMonth(1, 2012));
console.log(getDaysInMonth(2, 2012));
console.log(getDaysInMonth(9, 2012));
console.log(getDaysInMonth(12, 2012));

Output :
31
29
30
31

Solution

function getDaysInMonth(month, year) {
  let date = new Date(year, month, 0); // last day is represented by 0
  return date.getDate(); 
}

console.log(getDaysInMonth(1, 2012)); // 31
console.log(getDaysInMonth(2, 2012)); // 29
console.log(getDaysInMonth(9, 2012)); // 30
console.log(getDaysInMonth(12, 2012));// 31
console.log(getDaysInMonth(10, 2020)); // 31

Resouces

1. MDN - Date
2. JavaScript Date - Exercises, Practice, Solution