JS Practice — Built-in Objects

Type Guard — isBoolean

📖 Usage Example

function isBoolean(x: unknown): x is boolean {
  return typeof x === 'boolean'
}
isBoolean(true)   // → true
isBoolean(1)      // → false

typeof x === 'boolean' checks for exactly true or false, not truthy/falsy values.

Type Guards: isBoolean

Challenge: Implement isBoolean(x: unknown): x is boolean.

isBoolean(true)   // → true
isBoolean(false)  // → true
isBoolean(1)      // → false  (1 is truthy, not boolean)

💡 Hints (1)