Method to add delays at any position in Greensocks TimelineLite and TimelineMax (Javascript GSAP)

TimelineLite.addDelay.js

/**
 * Add a delay at the end of the timeline (or at any label)
 * @param {number} delay    Seconds to wait
 * @param {string} position Label name where to start the delay
 * 
 * Usage: tl.addDelay(4); //easy!
 */
TimelineLite.prototype.addDelay = function (delay, position) {
	var delayAttr;
	if(typeof delay === 'undefined' || isNaN(delay)){
		return this;//skip if invalid parameters
	}
	if (typeof position === 'undefined') {
		delayAttr = '+=' + delay; //add delay at the end of the timeline
	} else if (typeof position === 'string') {
		delayAttr = position + '+=' + delay; //add delay after label
	} else if(!isNaN(position)) {
		delayAttr = delay + position; //if they're both numbers, assume absolute position
	} else {
		return this; //nothing done
	}

	return this.set({}, {}, delayAttr);
};