String.toUpperCase() — run online

String

String.toUpperCase()

Converts a string to uppercase according to Unicode rules

→ stringPHP: strtoupper()ES1+

stringstring

String to convert

(string).toUpperCase()

RESULT

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Parameter Reference

Parameter	Type	Status	Description
string	string	required	String to convert

About

toUpperCase() converts all characters to uppercase following Unicode rules. Works with Cyrillic, Latin, Greek, and other alphabets. Returns a new string. For locale-specific rules (e.g. Turkish i → İ), use toLocaleUpperCase().

Browser Support

Available since ES1 (1997). In German "ß".toUpperCase() === "SS" — string length can increase.

Tips & Gotchas

For case-insensitive comparison: str1.toLowerCase() === str2.toLowerCase()
German "ß".toUpperCase() === "SS" — string can get longer
for Turkish use toLocaleUpperCase("tr").