The toLocaleUpperCase task converts a string value to uppercase according to locale-specific case mappings. The locale is based on the language settings of the browser. For most languages this task functions identically to toUpperCase and produces the same output; however, certain languages may behave differently — for example, Turkish has case mappings that differ from the default Unicode case mappings.
Suppose you have a dataset in lowercase format and you want to display it in uppercase. Use the toLocaleUpperCase task to convert the entire dataset to uppercase characters.
In this example, str is given the reference variable "hello world" in lowercase letters. The locale variable is only populated for languages such as Turkish, which require specific letter capitalizations for meaning.
The outgoing result shows all letters converted to uppercase: "HELLO WORLD".
For more information, see the Locale article on MDN.