Gets the key identifier of a key that is pressed.
- Document Object Model (DOM) Level 3 Events Specification, Section 5.2.6
Key identifiers are strings that uniquely identify keyboard buttons, such as
F2. The string can be any of the following types:
- Character string: A single character, such as a letter or symbol
- Key name: A multicharacter string such as
- Unicode codepoint: "U+" followed by a hexadecimal character index