toUpperCase method

  1. @useResult
List<String>? toUpperCase()

Returns a new list with every element uppercased (invariant culture).

Casing is locale-independent: Turkish 'i' uppercases to 'I', never the dotted 'İ'. Dart's String.toUpperCase() is a 1:1 code-point mapping and does NOT special-case the German eszett, so 'ß' stays 'ß' (it is NOT expanded to 'SS'). Surrogate pairs and emoji round-trip unchanged. Does not mutate the receiver.

Example:

['Ab', 'cd'].toUpperCase(); // ['AB', 'CD']

Audited: 2026-06-12 11:26 EDT

Implementation

@useResult
List<String>? toUpperCase() => map((String e) => e.toUpperCase()).toList();