CSS Transitionend Events: Multiple Transitions & Syncing JS

Rob will have you saying “Hello” to the right solution and “Bye” to `transitionend` headaches. I was recently working on some code that would handle a toggling menu’s open-close state after the animation had finished. In order to do this, we used the transitionend event to determine when we should modify the state of the DOM nodes to show the new state correctly. However, when the animation was en