Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
KeyboardEvent.keyIdentifier read-only property returns a "key identifier" string that can be used to determine what key was pressed. Its non-deprecated replacement is
Not part of any current specification. This property was part of an old draft of the DOM Level 3 Events Specification, but it was removed in later drafts in favor of
BCD tables only load in the browser