One of my favourite JavaScript libraries that I use when animating text is Splitting. Actually it doesn't handle any animations but it gives you the elements and tools needed to create animations & transitions and I do that only by CSS.
Here you can read the guide and get started with it. I would also share with you an example how you can create awesome text animations in a really simple way.
Splitting should be thought of as a progressive enhancer. The basic functions work in any halfway decent browser (IE11+). Browsers that support CSS Variables ( ~85% of the current browser market share ) will have the best experience. Browsers without CSS Variable support can still have a nice experience with at least some animation, but features like index-based staggering may not be feasible without JavaScript.
Splitting is easily expandable to create your own splits. Have fun and try it by yourself!