Function assertUnreachable

assertUnreachable(x: never): never

Verifies, that the given code path is never reached.

Parameters

x: never

Returns never

Example

type Shape = Circle | Square;
function area(s: Shape): number {
  switch(s.type) {
    case 'circle': return Math.PI * s.radius ** 2;
    case 'square': return s.sideLength ** 2;
    default:       return assertUnreachable(s); // ensures that all cases are covered
  }
}