JS Practice — Built-in Objects

Type Guard — isStringArray

📖 Usage Example

function isStringArray(x: unknown): x is string[] {
  return Array.isArray(x) && x.every(item => typeof item === 'string')
}
isStringArray(['a', 'b'])   // → true
isStringArray([1, 'a'])    // → false

Combining Array.isArray with every() lets you narrow the element type of an array.

Type Guards: isStringArray

Challenge: Implement isStringArray(x: unknown): x is string[] — every element must be a string.

isStringArray(['a', 'b', 'c'])  // → true
isStringArray(['a', 1, 'c'])    // → false

💡 Hints (1)

• Array.isArray + every(item => typeof item === "string").