js-custom-datepicker/src/js/lib/date.js

Сalendar was written on javascript using es6 format and was redone to es5 using webpack and babel tools. There are many classes for easy styling for the desired website design.

'use strict';

if (!Date.prototype.format) {

    Date.prototype.getMonthName = function () {
        let month_names = [
            'January',
            'February',
            'March',
            'April',
            'May',
            'June',
            'July',
            'August',
            'September',
            'October',
            'November',
            'December'
        ];

        return month_names[this.getMonth()];
    };

    Date.prototype.getMonthAbbr = function () {
        let month_abbrs = [
            'Jan',
            'Feb',
            'Mar',
            'Apr',
            'May',
            'Jun',
            'Jul',
            'Aug',
            'Sep',
            'Oct',
            'Nov',
            'Dec'
        ];

        return month_abbrs[this.getMonth()];
    };

    Date.prototype.getDayFull = function () {
        let days_full = [
            'Sunday',
            'Monday',
            'Tuesday',
            'Wednesday',
            'Thursday',
            'Friday',
            'Saturday'
        ];
        return days_full[this.getDay()];
    };

    Date.prototype.getDayAbbr = function () {
        let days_abbr = [
            'Sun',
            'Mon',
            'Tue',
            'Wed',
            'Thur',
            'Fri',
            'Sat'
        ];
        return days_abbr[this.getDay()];
    };

    Date.prototype.getDayOfYear = function () {
        let onejan = new Date(this.getFullYear(), 0, 1);
        return Math.ceil((this - onejan) / 86400000);
    };

    Date.prototype.getDaySuffix = function () {
        let d = this.getDate();
        let sfx = ["th", "st", "nd", "rd"];
        let val = d % 100;

        return (sfx[(val - 20) % 10] || sfx[val] || sfx[0]);
    };

    Date.prototype.getWeekOfYear = function () {
        let onejan = new Date(this.getFullYear(), 0, 1);
        return Math.ceil((((this - onejan) / 86400000) + onejan.getDay() + 1) / 7);
    };

    Date.prototype.isLeapYear = function () {
        let yr = this.getFullYear();

        if ((parseInt(yr) % 4) === 0) {
            if (parseInt(yr) % 100 === 0) {
                if (parseInt(yr) % 400 !== 0) {
                    return false;
                }
                if (parseInt(yr) % 400 === 0) {
                    return true;
                }
            }
            if (parseInt(yr) % 100 !== 0) {
                return true;
            }
        }
        if ((parseInt(yr) % 4) !== 0) {
            return false;
        }
    };

    Date.prototype.getMonthDayCount = function () {
        let month_day_counts = [
            31,
            this.isLeapYear() ? 29 : 28,
            31,
            30,
            31,
            30,
            31,
            31,
            30,
            31,
            30,
            31
        ];

        return month_day_counts[this.getMonth()];
    };

    Date.prototype.format = function (dateFormat) {

        let _dateFormat = dateFormat || 'dd-mm-YYYY';



        dateFormat = _dateFormat.split("");

        let date = this.getDate(),
                month = this.getMonth(),
                hours = this.getHours(),
                minutes = this.getMinutes(),
                seconds = this.getSeconds();
        let date_props = {
            d: date < 10 ? '0' + date : date,
            D: this.getDayAbbr(),
            j: this.getDate(),
            l: this.getDayFull(),
            S: this.getDaySuffix(),
            w: this.getDay(),
            z: this.getDayOfYear(),
            W: this.getWeekOfYear(),
            F: this.getMonthName(),
            m: month < 9 ? '0' + (month + 1) : month + 1,
            M: this.getMonthAbbr(),
            n: month + 1,
            t: this.getMonthDayCount(),
            L: this.isLeapYear() ? '1' : '0',
            Y: this.getFullYear(),
            y: this.getFullYear() + ''.substring(2, 4),
            a: hours > 12 ? 'pm' : 'am',
            A: hours > 12 ? 'PM' : 'AM',
            g: hours % 12 > 0 ? hours % 12 : 12,
            G: hours > 0 ? hours : "12",
            h: hours % 12 > 0 ? hours % 12 : 12,
            H: hours,
            i: minutes < 10 ? '0' + minutes : minutes,
            s: seconds < 10 ? '0' + seconds : seconds
        };

        let date_string = "";

        let prev_key = '';
        for (let i = 0; i < dateFormat.length; i++) {

            let f = dateFormat[i];

            if (prev_key === f) {
                continue;
            }
            if (f.match(/[a-zA-Z]/g)) {
                date_string += date_props[f] ? date_props[f] : '';
            } else {
                date_string += f;
            }
            prev_key = f;
        }




        return date_string;
    };
}

if (!Date.prototype.adjustDate) {
    Date.prototype.adjustDate = function (days) {
        let date;

        days = days || 0;


        if (days === 0) {
            date = this.getTime();
        } else if (days > 0) {
            date = this.getTime() + Math.abs(days * 86400000);
        } else {
            date = this.getTime() - Math.abs(days * 86400000);
        }

        this.setTime(date);
        this.setHours(0);

        return this;

    };
}