JS Practice — Built-in Objects

String.prototype.toLocaleUpperCase() — already uppercase

📖 Usage Example

'hello'.toLocaleUpperCase()   // → 'HELLO'
'world'.toLocaleUpperCase()   // → 'WORLD'
'abc123'.toLocaleUpperCase()  // → 'ABC123'

Use toLocaleUpperCase() to convert a string to uppercase using the locale-specific rules of the host environment.

String.prototype.toLocaleUpperCase() — Already Uppercase

If the string is already uppercase, toLocaleUpperCase() returns an equal string.

Challenge: Implement ensureUpper(str) and verify it works on already-uppercase strings.

ensureUpper('HELLO') // → 'HELLO'

💡 Hints (1)