JS Practice — Built-in Objects

String.prototype.toUpperCase() — all lowercase to uppercase

📖 Usage Example

'hello world'.toUpperCase()   // → 'HELLO WORLD'
'abc'.toUpperCase()           // → 'ABC'
'xyz123'.toUpperCase()        // → 'XYZ123'

Use toUpperCase() to convert all alphabetical characters in a string to uppercase.

String.prototype.toUpperCase()

str.toUpperCase() returns a new string with all letters converted to uppercase.

Challenge: Implement upper(str) that converts a string to uppercase.

upper('hello') // → 'HELLO'
upper('world') // → 'WORLD'

💡 Hints (1)