How can you survive a project that uses JavaScript massively on both the client and the server using Node.js? The project is about online development components, such as the TypeScript playground (http://www.typescriptlang.org/Playground/) or Visual Studio Online “Monaco," that enables users to edit Azure web sites online. We had an existing large JavaScript code base and we wanted to give TypeScript a try. Today the project is one of the largest TypeScript code bases inside Microsoft with more than 200k lines of TypeScript in production. In this talk I will give a quick introduction into TypeScript and then take a deep look at how TypeScript and other technologies were used to successfully scale up a very large JavaScript project.