Comment by thelarkinn

For sure! That's our preferred way of using JavaScript. TypeScript in the end is just a static type linter that compiles to JS. Heck you can even "use" TypeScript's typechecker without even using a .ts file. We do this for the webpack project using JSDOC Annotations (Project: https://github.com/webpack/webpack, Example: https://github.com/webpack/webpack/blob/master/lib/ChunkTemp...) because we didn't want a build step.