Unknown to Upper

any lets anything through and can hide bugs. unknown is safer: you must check before you use it. Here you will accept an unknown value and return uppercase text only when it is a string.

Use typeof x === 'string' to narrow. Return a default when the value is not a string. Keep the function small and pure.

function toLowerIfString(x: unknown) {
  return typeof x === "string" ? x.toLowerCase() : "";
}

Your Task

Implement a function that uppercases a value only when it is a string.

• Write function shout(x: unknown): string.
• If x is a string, return x.toUpperCase().
• Otherwise return an empty string ''.
• Do not mutate the input.