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The compositionend event is fired when the composition of a passage of text has been completed or cancelled (fires with special characters that require a sequence of keys and other inputs such as speech recognition or word suggestion on mobile).
[1] The event was fired in versions of Gecko before 9.0, but didn't have the DOM Level 3 attributes and methods. Gecko doesn't support the locale attribute for trusted events yet. However, this value can be set via initCompositionEvent() when creating untrusted events.