TypeScript's type system has grown steadily more powerful over the past five years, allowing you to precisely type more and more patterns in JavaScript. The upcoming TypeScript 4.1 release includes a particularly exciting new addition to the type system: template literal types. Template literal types solve a long-standing gap in TypeScript's type system and, as I'll argue at the end of the post, they solve it in a particularly TypeScripty way. To understand template literal types, let's start...
