Util date extensions

dateExtensions.js

//  Remember to prototype your own custom Date
var customDate = Date

//  Date extension to to make monday day 0 (week start on monday)
customDate.prototype.getDayL = function () {
	if ( this.getDay() == 0 ) {
		return 6;
	}else{
		return this.getDay() - 1;
	}
}
//  Date extension to get number of week in month
customDate.prototype.getWeekMonth = function (){
	var first = new Date( this.getFullYear(), this.getMonth(), 1 );
	return Math.ceil( ( this.getDate() + first.getDayL() ) / 7 );
}

// Date extension to get number of week in year
customDate.prototype.getWeekYear = function (){
	var first = new Date( this.getFullYear(), 0, 1 );
	return Math.ceil( ( this.getDayYear() + first.getDay() ) / 7 );
	/* if weeks starts on monday using getDayL extension */
	// return Math.ceil( ( this.getDayYear() + first.getDayL() ) / 7 );
}

// Date extension to get number of day in year
customDate.prototype.getDayYear = function (){
	var first = new Date( this.getFullYear(), 0, 1 );
	var diff = this - first;
	var oneDay = 1000 * 60 * 60 * 24;
	return diff / oneDay;
}

// Date extension to get number of days in month
customDate.prototype.getDaysInMonth = function (month, year){
	return new Date(year, month, 0).getDate();
}