How is it reinventing the wheel if there are already millions of LOC out there that use it? This is a debugging/development feature. The pre-processor already e

How is it reinventing the wheel if there are already millions of LOC out there that use it? This is a debugging/development feature. The pre-processor already exists, but if you can iterate rapidly without having to run it and without having to hassle with stuff like source maps, that's a huge workflow improvement. Even without these type annotations any production javascript of moderate size is already getting minified and compressed before deployment regardless of whether type hints are used. Right now when I'm authoring typescript in vscode, I get live error feedback from tsc and eslint in the editor, so in practice I only need to run tsc to "build" because I need to strip out all the typescript syntax. If that syntax became usable in a modern browser I could skip that build step during development and only run it for deploys to CI, staging and production.