Are transpilers included in Vanilla JS? If not, then IE 11 and Edge prior to 15 don't support async/await, which would mandate two codebases for lots of use-cas

Are transpilers included in Vanilla JS? If not, then IE 11 and Edge prior to 15 don't support async/await, which would mandate two codebases for lots of use-cases. Similarly, lots of other stuff has uneven support, hence polyfill, which also isn't "Vanilla JS" sensu stricto.