A highly performant way to add days or date range (array) in JavaScript

getDateRange.js

/**
 * Date.prototype.addDays
 * 
 */
Date.prototype.addDays = function( days ) {
	var element = new Date( this.valueOf() );
	element.setDate( element.getDate() + days );
	return element;
}
 
/**
 * Date.prototype.getDateRange
 * 
 */
Date.prototype.getDateRange = function( start, end, interval ) {
	interval = interval || 1;
	var dateRange = [], start = new Date( start ), end = new Date( end );
	while ( start <= end ) {
		dateRange.push( start );
		start = Date.prototype.addDays.call( start, interval );
	}
	return dateRange;
}

/**
 * DEMO
 */
var dateArray = Date.prototype.getDateRange(new Date(), new Date().addDays(7));
console.log(dateArray);