JS Practice — Built-in Objects

String.prototype.toLowerCase() — already lowercase unchanged

📖 Usage Example

'HELLO World'.toLowerCase()   // → 'hello world'
'ABC'.toLowerCase()           // → 'abc'
'XYZ123'.toLowerCase()        // → 'xyz123'

Use toLowerCase() to convert all alphabetical characters in a string to lowercase.

String.prototype.toLowerCase() — Already Lowercase

If all letters are already lowercase, toLowerCase() returns an equivalent string.

Challenge: Implement ensureLowercase(str) using toLowerCase.

ensureLowercase('hello') // → 'hello'

💡 Hints (1)