The best replacement for typescript is coffeescript.

The best alternatives to typescript are rated as following:
★★★★★  coffeescript
★★★★★  dart
★★  es6
★★  ecmascript 6
★  traceur
★  clojurescript
★  actionscript
  manuscript

Your alternative for typescript is not listed? Suggest!
Speaking about typescript, one probably shouldn't forget about angularjs.

Other search terms related to typescript and their ratings are:
★★★★★ angularjs
★★★★ knockout
★★★★ requirejs
★★ durandal
You have in mind a companion for typescript and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of typescript in all years. Click on graph for more.
typescript
coffeescript
dart