Extensions for momentjs This is a small extension to moment.js, and adds the ability to add/subtract number of business days, snap to nearest business day, and calculate difference in terms of business days. Note that this simply excludes Sundays and Saturdays.

momentjs-extensions.js

/* jshint laxbreak: true */
/**
 * moment.js plugin: additional methods
 * businessDiff (mStartDate)
 * businessAdd (numberOfDays)
 * businessSubtract (numberOfDays)
 * business ([false])
 */
(function () {
	var moment;
	moment = (typeof require !== "undefined" && require !== null) 
        && !require.amd 
        ? require("moment") 
        : this.moment;

	moment.fn.businessDiff = function (start) {
		var a, b, c,
            iDiff = 0,
			unit = 'day',
            iDiffDays = this.diff(start, unit);
        
		if (this.isSame(start)) return iDiff;

		if (this.isBefore(start)) {
			a = start.clone();
			b = this.clone();
			c = -1;
		} else {
			a = this.clone();
			b = start.clone();
			c = 1;
		}

		do {
			var iDay = b.day();
			if (iDay > 0 && iDay < 6) {
				iDiff++;
			}
			b.add(unit, 1);
		} while (a.diff(b, unit) > 0);

		return iDiff * c;
	};

	moment.fn.businessAdd = function (days) {
		var i = 0;
		while (i < days) {
			this.add('day', 1);
			if (this.day() > 0 && this.day() < 6) {
				i++;
			}
		}
		return this;
	};

	moment.fn.businessSubtract = function (days) {
		var i = 0;
		while (i < days) {
			this.subtract('day', 1);
			if (this.day() > 0 && this.day() < 6) {
				i++;
			}
		}
		return this;
	};
	
	moment.fn.business = function (backwards) {
		while (this.day() === 0 || this.day() == 6) {
			this[!!backwards ? 'businessSubtract' : 'businessAdd'](1);
		}
		return this;
	};
	
}).call(this);

Those iteration looped solutions would not fit my needs.
They were too slow for large numbers.
So I made my own version:

https://github.com/leonardosantos/momentjs-business

Hope you find it useful.