removeLetters method Null safety

String? removeLetters()

Removes only the letters from the String.

Example 1

String foo = 'es4e5523nt1is';
String noLetters = foo.removeLetters() // returns '455231'

Example 2

String foo = '1244e*s*4e*5523n*t*1i*s'
String noLetters = foo.removeLetters() // returns '1244**4*5523**1*'

Implementation

String? removeLetters() {
  if (this == null) {
    return null;
  }
  if (this!.isEmpty) {
    return this;
  }
  // ignore: unnecessary_raw_strings
  var regex = RegExp(r'([a-zA-Z]+)');
  return this!.replaceAll(regex, '');
}