JavaScript datetime object helper functions

A collection of helper functions for using JavaScript datetime object.

var getCurrentDate = function(){
    // Get the current date
    var today = new Date();

    // Extract day
    var day = today.getDate();
    // Add leading zero if day is a single digit
    if(day < 10){
        day = '0' + day;
    }

    // Extract month
    var month = today.getMonth() + 1; // Months are zero-based
    // Add leading zero if month is a single digit
    if(month < 10){
        month = '0' + month;
    }

    // Format the date as DD.MM.YYYY
    var date = day + '.' + month + '.' + today.getFullYear();

    // Return the formatted date
    return date;
};


// Example usage
var currentDate = getCurrentDate();
console.log("Current Date: " + currentDate); // Current Date: 12.11.2019

var isValidDateObject = function(dt) {
    // Make sure the input is a valid Date object
    if (!(dt instanceof Date) || isNaN(dt)) {
        return false;
    }

    // If the date is valid, return true
    return true;
};


// Example usage
var validDate = new Date(); // a valid Date object
var invalidDate = "not a date"; // not a valid Date object

// Check if the values are valid Date objects
console.log("Is validDate a valid Date object? " + isValidDateObject(validDate)); // Should print: true
console.log("Is invalidDate a valid Date object? " + isValidDateObject(invalidDate)); // Should print: false

var getDateObjectFromDateString = function(dateString) {
    // Extract components
    var dateComponents = dateString.split(".");
    var day = parseInt(dateComponents[0], 10);
    var month = parseInt(dateComponents[1], 10) - 1; // Months are zero-based
    var year = parseInt(dateComponents[2], 10);
   
    // Create Date object
    var dateObject = new Date(year, month, day);
   
    // Check if the date object is valid
    if (!isValidDateObject(dateObject)) {
        // If the date is invalid, return false
        return false;
    }

    // If the date is valid, return the Date object
    return dateObject;
};

// Example usage
var dateString = "12.11.2019";
var dateObject = getDateObjectFromDateString(dateString);

if (dateObject) {
    console.log("Date object created:", dateObject);
} else {
    console.log("Invalid date string");
}

var subtractSecondsFromDate = function(dt, secondsToSubtract) {
    // Make sure the input is a valid Date object
    if (!isValidDateObject(dt)) {
        return false;
    }

    // Calculate the new time in milliseconds
    var newTime = date.getTime() - secondsToSubtract * 1000;

    // Create a new Date object with the adjusted time
    var newDate = new Date(newTime);

    return newDate;
};

// Example usage: Calculate the date 1 year ago
var currentDate = new Date();
var secondsInOneYear = 365 * 24 * 60 * 60; // Assuming a non-leap year
var oneYearAgo = subtractSecondsFromDate(currentDate, secondsInOneYear);

console.log("Current Date:", currentDate);
console.log("Date 1 year ago:", oneYearAgo);

var formatDateStr = function(str){
    // Trim leading and trailing whitespaces
    var dt = str.trim();

    // Split the date string into an array of components
    var sp = dt.split('.');

    // Reformat the date string to "YYYY-MM-DDTHH:mm:ss"
    return sp[2] + '-' + sp[1] + '-' + sp[0] + 'T00:00:00';
};

// Example usage
var inputDate = "12.11.2019";
var formattedDate = formatDateStr(inputDate);

console.log("Original Date String:", inputDate); // 12.11.2019
console.log("Formatted Date String:", formattedDate); // 2019-11-12T00:00:00

var daysBetween = function(date1, date2) {
    try {
        // Convert the dates to milliseconds.
        var ms1 = date1.getTime();
        var ms2 = date2.getTime();
       
        // Calculate the difference in milliseconds.
        var diff = ms2 - ms1;
       
        // Divide the difference by the number of milliseconds in a day.
        var days = diff / (1000 * 60 * 60 * 24);
       
        // Return the absolute value of the difference in days.
        return Math.floor(days);
    } catch (errMsg) {
        // Handle any potential errors (though not clear what error might occur here).
    }
    
    // Return 0 if an error occurs or if there is no difference in days.
    return 0;
};

// Example usage
var startDate = new Date("2019-01-01");
var endDate = new Date(); // Current date

var daysDifference = daysBetween(startDate, endDate);

console.log("Start Date:", startDate.toISOString()); // Start Date: 2019-01-01T00:00:00.000Z
console.log("End Date:", endDate.toISOString()); // End Date: 2019-11-13T13:10:12.574Z
console.log("Days Between:", daysDifference); //  Days Between: 316