In order to provide better samples for our TypeScript users, new samples going forward will be written in TypeScript, in this directory. npm run compile will take care of all the steps needed to merge the existing JavaScript samples into build/ along with the converted TypeScript samples. The system sample tests will then use build/ for its testing.
Note that the files tsc builds from this tree will not be used; this is just to do strict type checking.
When you are ready to submit a PR for the updated sample, OwlBot will take care of regenerating any *.js files from the *.ts files.