microsoft/TypeScript ? reverse-engineered prompt

I want to create a new programming language that's a superset of JavaScript, designed to make it easier to build and maintain large-scale applications. The key feature should be adding optional static types to the language. This will allow developers to catch common errors early, right in their code editor, like trying to use a string where a number is expected.

The language should compile down to clean, readable, standards-compliant JavaScript that can run in any browser or on any Node.js server. It should also provide a language service that can power rich editor features like intelligent code completion, refactoring, and error checking. Please make sure the whole thing can be packaged and distributed as an npm module for easy installation in other projects.