substringBefore method

String substringBefore(
  1. String delimiter, {
  2. String? missingDelimiterValue,
})

Returns a substring before the first occurrence of delimiter.

Example:

'user@example.com'.substringBefore('@'); // 'user'

Implementation

String substringBefore(String delimiter, {String? missingDelimiterValue}) {
  final index = indexOf(delimiter);
  return index == -1 ? (missingDelimiterValue ?? this) : substring(0, index);
}