Please forgive the lack of a pen. Deadline– ... It's gonna work like this! I promise–   var tl = new TimelineMax() .to(elem, 1, { y: function() { return $(window).height() / 100 * 50; } }); $(window).on("resize", function() { // refresh the timelines tween });   How can I force tl to execute the tweens function and therefore recalculate the y-value?     Thank you for your help!