TypeScript is a superset of JavaScript, so if you're comfortable with oop, then the learning curve isn't going to be very different either way. However, since ts needs to be precompiled to js before it can be rendered on the web, it might be beneficial to use .d.ts files for all of your type checking but use js files for everything else in the application. You can also use jsdoc, to do a lot of the things typescript can do while developing or testing the app, so that may be a good solution depending on how strict your app is about type safety. You can also use them together and try to find a balance between them based on what works best for your application.