Well Typescript is really a static code analyser for Javascript and not a language, since it does nothing at runtime, and that's fine, its type system can catch

Well Typescript is really a static code analyser for Javascript and not a language, since it does nothing at runtime, and that's fine, its type system can catch a broad range of issues and improve code quality drastically. It's a huge godsend for big codebases. But afaik it doesn't guard against null by default. A simpler example: declare type Foo = {name:String}; declare function getFoo():Foo|null; const f = getFoo(); if(f!==null) // mandatory or yields an error console.log(f.name); But afaik it doesn't guard against null by default.