JS Practice — Built-in Objects

String.prototype.toLowerCase() — numbers and symbols 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() — Numbers Unchanged

Digits, spaces, and symbols are not affected by toLowerCase().

Challenge: Implement lowerAlpha(str) that lowercases only the letters.

lowerAlpha('ABC 123!') // → 'abc 123!'

💡 Hints (1)

• Only letter characters are converted; numbers, symbols, and spaces are left as-is.