What Typescript type is a change event? (In Angular)

It is an event. But you’re going to have to cast the const you’re using as an HTMLInputElement.

public onChange(event: Event): void {
  if ((event.target as HTMLInputElement).files && (event.target as HTMLInputElement).files.length) {
    const [file] = event.target.files;
  }
}

The only other way is going to be to suppress the error with tsignore. In react, flow, they have a type SyntheticEvent that you can type this particular case as to get around it but angular doesn’t have a real equivalent.