Any programmer working in a dynamically typed language will tell you how hard it is to scale that language to more lines of code and to more engineers. That's why Facebook, Google, and Microsoft invented gradual static type layers for their dynamically typed JavaScript and Python code. TypeScript is one such type layer, and does something unique among them: it makes programming fun with its powerful, modern, static type system. With this book, programmers who understand JavaScript at an intermediate level will learn how to master the TypeScript language. You'll understand how TypeScript can help you get rid of bugs in your code, scale your code across 10x more engineers, and make programming fun again.