One more thing that IMO gets overlooked too often: TypeScript can typecheck your JSX markup. Compare that to any string-based templating engine, such as Knockout.js templates or jquery.tmpl, where you have to learn its snowflake DSL, you get no autocomplete, no checks for undefined variables or syntax errors…
If I never have to explain <!-- ko if: !condition --> vs <!-- ko ifnot: condition --> again, I'll be a happy man.
This is the type of thing to which I was referring. A server interface is updated to return a different data type or renamed, the client shares the same interface, type checking for TSX (TypeScript JSX) catches the name or type of the property is invalid, and you can immediately fix it.
No more grepping an entire codebase to see all the places that something is referenced and praying that you updated all of them. (And praying that you updated them correctly!)
If I never have to explain <!-- ko if: !condition --> vs <!-- ko ifnot: condition --> again, I'll be a happy man.