One of the things I appreciate most about TypeScript is how it transforms the developer experience. Autocomplete, inline documentation, and type checking make it harder to shoot yourself in the foot with something as simple as a typo. But that benefit only exists when the libraries you use ship with type definitions, or when someone takes the time to create them.

In a previous project I had to use a web component that communicated with the rest of an Angular application through events. This component was closed and I could not modify it, but it was configurable through input parameters that allowed to modify the detail of the events that were issued.