Typescript: How to import classes ("Uncaught ReferenceError")

I had a similar issue, and it was due to the html file not importing all the javascript files. To solve your situation you would add Vehicle.js, Car.js and Boat.js to your index.html file.

I suspect your project is set to compile each .ts file into a separate .js file. If this is the case then only Main.js will be loaded, but boat.js, car.js, etc won't have, giving you an error.

If you change your project to compile the output into a single file then the TypeScript compiler will use the <reference> tags to pull in the other .ts files and build a single .js file you can reference with a tag.

If you're using Visual Studio there is an option 'Combine JavaScript output into file" under TypeScript Build of your project settings. If you using the command line compiler then the --out flag can be used to produce a single file - see http://www.typescriptlang.org/Handbook#modules-splitting-across-files for more info.