description

# toUpperCase method Null safety

String toUpperCase ()

Converts all characters in this string to upper case. If the string is already in all upper case, this method returns `this`.

    'alphabet'.toUpperCase(); // 'ALPHABET'
    'ABC'.toUpperCase();      // 'ABC'

This function uses the language independent Unicode mapping and thus only works in some languages.

## Implementation

    // TODO(floitsch): document better. (See EcmaScript for description).
    String toUpperCase();