Java on dates

JDate: Date/time

Don't forget to check the documentation for the JDate Class

JS : Retrieving the week number (from Monday to Sunday)

function getWeekNumber(d) {
    // Copy date
    d = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
    // Set to nearest Thursday: current date + 4 - current day number
    // Make Sunday's day number 7
    d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay()||7));
    // Get first day of year
    var yearStart = new Date(Date.UTC(d.getUTCFullYear(),0,1));
    // Calculate full weeks to nearest Thursday
    var weekNo = Math.ceil(( ( (d - yearStart) / 86400000) + 1)/7);
    // Return array of year and week number
    return [d.getUTCFullYear(), weekNo];
}

let MyDate = new Date(Date.parse("2020-04-04 15:13:00"));

var WeekNumber = getWeekNumber(MyDate)[1];
//result : WeekNumber = "14"

JS : Transform millisecond timestamp into date format YYYYMMDD_HHMMSS

function formatDate(timestamp) {
    var date = new Date(timestamp);
    var seconds = date.getSeconds();
    var minutes = date.getMinutes();
    var hours = date.getHours();
    var day = date.getDate();
    var month = date.getMonth()+1;
    var year = date.getFullYear();
    seconds = ("0" + seconds).substr(("0" + seconds).length-2, 2);
    minutes = ("0" + minutes).substr(("0" + minutes).length-2, 2);
    hours = ("0" + hours).substr(("0" + hours).length-2, 2);
    day = ("0" + day).substr(("0" + day).length-2, 2);
    month = ("0" + month).substr(("0" + month).length-2, 2);
    return year + month + day + "_" + 
              hours + minutes + seconds;
    }
//get the current date (millisecond timestamp)
  let timestamp = new Date().getTime();

//Transform into date format YYYYMMDD_HHMMSS
  let Date1 =  formatDate(timestamp)

JS : Returning the day of the week

To transform the numbers in week days:

let MyDate = new Date(Date.parse("2021-01-11 15:13:00"));

let num_jour= MyDate.getDay();

// In French
let jour = "";
if (num_jour==1) {jour ="01-LUNDI"};
if (num_jour==2) {jour ="02-MARDI"};
if (num_jour==3) {jour ="03-MERCREDI"};
if (num_jour==4) {jour ="04-JEUDI"};
if (num_jour==5) {jour ="05-VENDREDI"};
if (num_jour==6) {jour ="06-SAMEDI"};
if (num_jour==7) {jour ="07-DIMANCHE"};

// In English
let jour = "";
if (num_jour==1) {jour ="01-MONDAY"};
if (num_jour==2) {jour ="02-TUESDAY"};
if (num_jour==3) {jour ="03-WEDNESDAY"};
if (num_jour==4) {jour ="04-THURSDAY"};
if (num_jour==5) {jour ="05-FRIDAY"};
if (num_jour==6) {jour ="06-SATURDAY"};
if (num_jour==7) {jour ="07-SUNDAY"};

JS : Returning the name of the month

const Date1 = new Date(Date.parse("2021-02-01 15:13:00"));
const months = ["January", "February","March","April","May","June","July","August","September","October","November","December"];
const monthDate1 = Date1.getMonth();

msg.payload = {
    "Date": Date1,
    "Month": monthDate1 +1,
    "Month_Name": months[monthDate1]
};

return msg;