No Duplicate Case - Denoland

Disallows using the same case clause in a switch statement more than once.

When you reuse a case test expression in a switch statement, the duplicate case will never be reached meaning this is almost always a bug.

Invalid:

typescript

const someText = "a";
switch (someText) {
  case "a": // (1)
    break;
  case "b":
    break;
  case "a": // duplicate of (1)
    break;
  default:
    break;
}

Valid:

typescript

const someText = "a";
switch (someText) {
  case "a":
    break;
  case "b":
    break;
  case "c":
    break;
  default:
    break;
}