keyCode property of key events
Event models
An implementation may choose to expose both virtual key codes and character codes in the keyCode property ('conflated model'), or report separate keyCode and charCode properties ('split model').
How to calculate keyCode for keydown and keyup events
The keyCode for keydown / keyup events is calculated as follows:
- Read the virtual key code from the operating system's event information, if such information is available.
- If an Input Method Editor is processing key input and the event is keydown, return 229.
- If input key when pressed without modifiers would insert a numerical character (0-9), return the ASCII code of that numerical character.
- If input key when pressed without modifiers would insert a a lower case character in the a-z alphabetical range, return the ASCII code of the upper case equivalent.
- If the implementation supports a key code conversion table for the operating system and platform, look up the value. If the conversion table specifies an alternate virtual key value for the given input, return the specified value.
- If the key's function, as determined in an implementation-specific way, corresponds to one of the keys in the table of fixed virtual key codes, return the corresponding key code.
- Return the virtual key code from the operating system.
- If no key code was found, return 0.
How to calculate keyCode for keypress events
The keyCode for keypress events is calculated as follows:
- If the implementation supports a 'conflated model', set keyCode to the Unicode code point of the character being entered.
- If the implementation supports a 'split model', set keyCode to 0.
Fixed virtual key codes
The virtual key codes for the following keys do not usually change with keyboard layouts on desktop systems:
| The key | virtual key code |
|---|
| Backspace | 8 |
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| Tab | 9 |
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| Enter | 13 |
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| Shift | 16 |
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| Control | 17 |
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| Alt | 18 |
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| Caps Lock | 20 |
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| Escape | 27 |
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| Space | 32 |
|---|
| Page up | 33 |
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| Page down | 34 |
|---|
| End | 35 |
|---|
| Home | 36 |
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| Left | 37 |
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| Up | 38 |
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| Right | 39 |
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| Down | 40 |
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| Delete | 46 |
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Optionally fixed virtual key codes
This section is informative
The following punctuation characters may change virtual codes between keyboard layouts, but reporting these values will likely be more compatible with legacy content expecting US-English keyboard layout:
| The key | virtual key code |
|---|
| Semicolon (;) | 186 |
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| Colon (:) | 186 |
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| Plus (+) | 187 |
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| Equals sign (=) | 187 |
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| Comma (,) | 188 |
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| Less than sign (<) | 188 |
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| Minus (-) | 189 |
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| Underscore (_) | 189 |
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| Period (.) | 190 |
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| Greater than sign (>) | 190 |
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| Question mark (?) | 191 |
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| Forward slash (/) | 191 |
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| Backtick (`) | 192 |
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| Tilde (~) | 192 |
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| Opening square bracket ([) | 219 |
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| Opening curly bracket ({) | 219 |
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| Backslash (\) | 220 |
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| Pipe (|) | 220 |
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| Closing square bracket (]) | 221 |
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| Closing curly bracket (}) | 221 |
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| Single quote (') | 222 |
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| Double quote (") | 222 |
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Acknowledgements
Thanks to Anne van Kesteren, Alexey Proskuryakov, Olli Pettay, Bjoern Hoehrmann and Oliver Hunt for comments on earlier (and more complicated) versions of this draft.
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