remaining-period-calculator/index.js

It calculates between the two periods

/**
 * @author Abdulrahman AL Saad
 * @classdesc It calculates between the two periods
 */
class remainingPeriodCalculator
{
    /**
     * 
     * @param {{timeZone:number,year:number,month:number,day:number}} options
     */
    constructor(options)
    {
        /**@private */ this.year;
        /**@private */ this.month;
        /**@private */ this.day;
        /**@private */ this.timeZone = 0;
        if(!options) options ={};
        else options = options;
        if(options.year) this.year = options.year;
        if(options.month) this.month = options.month;
        if(options.day) this.day = options.day;
        if(options.timeZone) this.timeZone = options.timeZone;
    }
    /**
     * 
     * @param {number} year 
     */
    remainingYears(year)
    {
        if(!year) year = this.getDate().year;
        return Math.abs(this.getDate().year - year);
    }
    /**
     * 
     * @param {number} month 
     * @param {number} year 
     */
    remainingMonths(month,year)
    {
        if(!month) month = this.getDate().month;
        if(!year) year = this.getDate().year;
        var calMonth = Math.abs(this.getDate().month - month);
        var calYear = this.remainingYears(year);
        if(this.getDate().month >= month && year > this.getDate().year) calMonth =  month +  (12 - this.getDate().month) ; 
        else if(this.getDate().month <= month && year < this.getDate().year) calMonth = this.getDate().month +  (12 - month) ;
        if((this.getDate().month >= month && year > this.getDate().year) || (this.getDate().month <= month && year < this.getDate().year)) calYear -=1;
        return calMonth + (12 * calYear);
    }
    /**
     * 
     * @param {number} day 
     * @param {number} month 
     * @param {number} year 
     */
    remainingDays(day,month,year)
    {
        if(!day) day = this.getDate().day;
        if(!month) month = this.getDate().month;
        if(!year) year = this.getDate().year; 
        var calMonth = this.remainingMonths(month,year);
        var calDay = Math.abs(this.getDate().day - day);
        if((this.getDate().day < day && this.getDate().month > month && year == this.getDate().year) ||
        (this.getDate().day <= day && year < this.getDate().year)) calDay = this.getDate().day + (30 - day);
        else if((this.getDate().day > day && this.getDate().month < month && year == this.getDate().year) ||
        (this.getDate().day >= day && year > this.getDate().year)) calDay = day + (30 - this.getDate().day);
        if((this.getDate().day > day && this.getDate().month < month && year == this.getDate().year) ||
        (this.getDate().day < day && this.getDate().month > month && year == this.getDate().year)||
        (this.getDate().day >= day && year > this.getDate().year)||
        (this.getDate().day <= day && year < this.getDate().year)) calMonth -=1;
        return calDay + (30 * calMonth);
    }
    /**@private */
    getDate()
    {
        var time = new Date();
        time = time.getTime() + (time.getTimezoneOffset() * 60000);
        time = new Date(time + (3600000 * this.timeZone));
        var toDate = time.toLocaleDateString().split("/");
        var year = this.year || parseInt(toDate[2]);
        var month = this.month || parseInt(toDate[0]);
        var day = this.day || parseInt(toDate[1]);
        return {day,month,year}
    }
}

module.exports = {remainingPeriodCalculator};