> since the main advantage of JavaScript is not having to supply types. With TypeScript and Dart, the type annotations are optional. You don't have to use them

> since the main advantage of JavaScript is not having to supply types. With TypeScript and Dart, the type annotations are optional. You don't have to use them. With JavaScript, you can't add any type information. Using non-standard doc comments is the only option. Also, the main advantage of JavaScript is that it's available in browsers.