upperCaseFirstChar method
Converts the first character of the string to uppercase, leaving the rest of the string unchanged.
If the string is empty, it returns an empty string.
Returns: A new string with the first character in uppercase, or an empty string if the original string is empty.
Example:
'mixedCase'.upperCaseFirstChar(); // Returns 'MixedCase'
'UPPERCASE'.upperCaseFirstChar(); // Returns 'UPPERCASE'
''.upperCaseFirstChar(); // Returns ''
Implementation
String upperCaseFirstChar() => isEmpty ? '' : this[0].toUpperCase() + substring(1);