As a professional web developer who uses TypeScript (disclaimer: MS employee, not on the TypeScript team), I don't find that it impacts in-browser debugging. Ty

As a professional web developer who uses TypeScript (disclaimer: MS employee, not on the TypeScript team), I don't find that it impacts in-browser debugging. TypeScript has the ability to generate map files, but we don't use it because issues with our tooling. I don't miss it though, because the generated JavaScript is pretty close to the TypeScript (we target ES5, if you can target ES6 the mangling is even less). Once you learn the common patterns (methods get mapped onto the prototype, fat arrow functions get compiled to regular functions with a _this variable) it's pretty straightforward to debug in the browser. The dev inner loop is maybe a little slower with the compile step for us, but it is possible to use TypeScript's automatic compilation with webpack and Node and all the latest hotness and get automatic build/deploy/refresh (see Office Fabric: https://github.com/OfficeDev/office-ui-fabric-react https://github.com/OfficeDev/office-ui-fabric-react)