In this codepen example I have five buttons, and a timeline with five labels.    When clicking on a button I want to move from the current location in the timeline, to the label corresponding to the button. In other words if you click on button 2, the animation should go from wherever it currently is to the point at label "two", so if it was previously at "one" the timeline should play forward from label "one" to "two", but if it was at position "three" it should play backwards from "three" to