Jalali date converter (needs jalali-moment library)

date.helper.ts

import * as moment from 'jalali-moment';

export class DateHelper {
    static monthsNames = [
        'فروردین',
        'اردیبهشت',
        'خرداد',
        'تیر',
        'مرداد',
        'شهریور',
        'مهر',
        'آبان',
        'آذر',
        'دی',
        'بهمن',
        'اسفند'
    ];

    static convert(value: Date | string, withTime: boolean = true): string {
        let str: string;
        let result: string;

        if (!value || value.toString().length === 0) {
            value = new Date();
        }

        if (typeof (value) !== 'string') {
            str = `${value.getFullYear()}-${value.getMonth() + 1}-${value.getDate()}`;
            if (withTime) {
                str += ` ${value.getHours()}:${value.getMinutes()}:${value.getSeconds()}`;
            }
        } else {
            str = value;
        }

        if (withTime) {
            result = this.fullConvert(str);
        } else {
            result = this.halfConvert(str);
        }

        return result;
    }

    static convertMonthAndYearForCalendar(value: Date | string) {
        let str: string;
        let result: string;

        if (value) {
            if (typeof (value) !== 'string') {
                str = `${value.getFullYear()}-${value.getMonth() + 1}-${value.getDate()}`;
            }

            const momentDate = moment(str, 'YYYY-MM-DD');
            result = momentDate.locale('fa').format('MMM jYYYY');
        }

        return result;

    }

    private static fullConvert(str: string): string {
        const momentDate = moment(str, 'YYYY-MM-DD HH:mm:ss');
        return momentDate.locale('fa').format('dddd، DD MMM jYYYY HH:mm:ss');
    }

    private static halfConvert(str: string): string {
        const momentDate = moment(str, 'YYYY-MM-DD');
        return momentDate.locale('fa').format('dddd، DD MMM jYYYY');
    }
}