Function _parsePosition

src/gsap-core.js:390–414

(animation, position, percentAnimation)

	_onUpdateTotalDuration = animation => (animation instanceof Timeline) ? _uncache(animation) : _setDuration(animation, animation._dur),
	_zeroPosition = {_start:0, endTime:_emptyFunc, totalDuration:_emptyFunc},
	_parsePosition = (animation, position, percentAnimation) => {
		let labels = animation.labels,
			recent = animation._recent || _zeroPosition,
			clippedDuration = animation.duration() >= _bigNum ? recent.endTime(false) : animation._dur, //in case there's a child that infinitely repeats, users almost never intend for the insertion point of a new child to be based on a SUPER long value like that so we clip it and assume the most recently-added child's endTime should be used instead.
			i, offset, isPercent;
		if (_isString(position) && (isNaN(position) || (position in labels))) { //if the string is a number like "1", check to see if there's a label with that name, otherwise interpret it as a number (absolute value).
			offset = position.charAt(0);
			isPercent = position.substr(-1) === "%";
			i = position.indexOf("=");
			if (offset === "<" || offset === ">") {
				i >= 0 && (position = position.replace(/=/, ""));
				return (offset === "<" ? recent._start : recent.endTime(recent._repeat >= 0)) + (parseFloat(position.substr(1)) || 0) * (isPercent ? (i < 0 ? recent : percentAnimation).totalDuration() / 100 : 1);
			}
			if (i < 0) {
				(position in labels) || (labels[position] = clippedDuration);
				return labels[position];
			}
			offset = parseFloat(position.charAt(i-1) + position.substr(i+1));
			if (isPercent && percentAnimation) {
				offset = offset / 100 * (_isArray(percentAnimation) ? percentAnimation[0] : percentAnimation).totalDuration();
			}
			return (i > 1) ? _parsePosition(animation, position.substr(0, i-1), percentAnimation) + offset : clippedDuration + offset;
		}
		return (position == null) ? clippedDuration : +position;
	},
	_createTweenType = (type, params, timeline) => {
		let isLegacy = _isNumber(params[1]),
			varsIndex = (isLegacy ? 2 : 1) + (type < 2 ? 0 : 1),