UI Events KeyboardEvent code Values

1. Introduction

This document provides an overview of the various keyboard layouts and specifies the code values that should be used for each of the keys. Unlike the key values described in [UIEvents-key], the code values are based only on the key’s physical location on the keyboard and do not vary based on the user’s current locale.

This specification was formerly titled DOM Level 3 KeyboardEvent code Values.

1.1. Stylistic Conventions

This specification uses the following conventions:

• The key cap or label printed on a key is shown as ↓, = or Q. This is used to refer to a key from the user’s perspective without regard for the key and code values in the generated KeyboardEvent.

• Glyphs representing character are shown as: "𣧂".

• Unicode code points are shown as: U+003D.

• Valid key attribute values (i.e., the value of a key attribute) are shown as: "ArrowDown", "=", "q" or "Q".

• Valid key code attribute values (i.e., the value of a code attribute) are shown as: "ArrowDown", "Equal" or "KeyQ".

2. Keyboard Layout

This section is non-normative.

Alphanumeric keyboards are the most common way for users to generate keyboard events. This section provides an overview of standard keyboards and their physical layouts.

2.1. Standard Keyboard Layouts

This section describes the physical layouts found on commonly available keyboards.

2.1.1. Keyboard Sections

When discussing keyboard layouts, it is convenient to divide the standard keyboard into distinct sections and to label each row.

These keyboard sections are:

• The alphanumeric section is the main part of the keyboard and is where most of the keyboard variation occurs. When a user selects a keyboard layout, it is the keys in this sections that are most affected.

• The control pad and arrow pad sections contain the arrow keys and other editing keys.

• The numpad (also known as the "numeric keypad" or "number pad") contains number and math keys to make it easier to enter numeric data.

• And finally, the function section contains miscellaneous function keys and special keys like Escape.

To make it easier to identify keys, the rows on the keyboard are named starting with "A" for the bottom row up to "E" for the top row. The row of keys in the function section are considered to be in row "K". These row names are consistent with those given in [ISO9995-1].

Note that many keyboards (both modern and legacy) have extra keys that do not fit neatly into the above sections. Some of these keys are covered in § 3.6 Media Keys.

2.1.2. Standard "101" Keyboard Layout

The standard "101" keyboard (commonly referred to as the "US layout") is the only layout that has a "Backslash" key (labeled \|) above a single-row Enter key. All the other layouts omit this key and expand the Enter key to occupy two-rows.

Modern standard "101"-layout keyboards actually contain 104 keys: 61 keys in the alphanumeric section and 43 keys in the numpad, control pad, arrow pad and function sections. The "101" name for this keyboard layout dates to the time when this standard keyboard did in fact contain 101 keys. The two Meta keys (commonly given an OS-specific label), and the Menu key were added later to bring the total to 104 keys.

2.1.3. Alternate "101" Keyboard Layout

The alternate "101" keyboard has a large Enter key and shrinks the Backspace key to make room for the "IntlYen" key (which replaces the "Backslash" key found in the standard 101 layout). The "IntlYen" name comes from the Japanese layout where this is the ¥ (yen) key — in the Russian layout shown below this key maps to a \/.

Modern alternate "101"-layout keyboards contain 104 keys: 61 keys in the alphanumeric section and 43 keys in the numpad, control pad, arrow pad and function sections.

2.1.4. Standard "102" Keyboard Layout

The standard "102" keyboard is common throughout Europe and adds a key that doesn’t exist on the "101" layouts: The "IntlBackslash" key (labelled \| on a UK keyboard) next to the left shift key.

A second key is also added (labelled #~ on a UK keyboard) which is partially tucked under the Enter key. This key is encoded as "Backslash", using the same code as the \| key found on the "101" keyboard layout. According to [USB-HID], the US \| and UK #~ are actually two separate keys (named "Keyboard \ and |" and "Keyboard Non-US # and ~"), but since these two keys never co-occur on the same keyboard most platforms use the same scancode for both keys, making them difficult to distinguish. It is for this reason that the code "Backslash" is used for both of these keys.

Modern "102"-layout keyboards contain 105 keys: 62 keys in the alphanumeric section and 43 keys in the numpad, control pad, arrow pad and function sections.

2.1.5. Korean "103" Keyboard Layout

The Korean "103" keyboard is based on the alternate 101 layout and adds two additional keys (one on each side of the spacebar) to handle Korean-specific input modes. These keys are "Lang2" ("Hanja", labelled 한자 hanja) and "Lang1" ("HangulMode", labelled 한/영 han/yeong).

Modern "103"-layout keyboards contain 106 keys: 63 keys in the alphanumeric section and 43 keys in the numpad, control pad, arrow pad and function sections.

2.1.6. Brazilian "104" Keyboard Layout

The "104" layout used in Brazil adds 4 new keys: two keys from the "102" layout ("Backslash" and "IntlBackslash") plus the "IntlRo" key (next to the right shift key) and an extra key on the numpad. This new numpad key is called "NumpadComma" because it represents the thousands separator. On the Brazilian key layout, this key is labelled . and the "NumpadDecimal" key is labelled ,.

Modern "104"-layout keyboards contain 107 keys: 63 keys in the alphanumeric section and 44 keys in the numpad, control pad, arrow pad and function sections. Some Brazilian keyboards lack the extra numpad key and have only 106 keys.

2.1.7. Japanese "106" Keyboard Layout

The Japanese "106" keyboard layout adds 3 new keys: "IntlYen" (labelled ¥_), "Backslash" (labelled ]む) and "IntlRo" (labelled \ろ). It also shrinks the spacebar to make room for 3 input mode keys: "NonConvert" (labelled 無変換 muhenkan), "Convert" (labelled 変換 henkan) and "KanaMode" (labelled カタカナ/ひらがな/ローマ字 katakana/hiragana/romaji).

Modern "106"-layout keyboards contain 109 keys: 66 keys in the alphanumeric section and 43 keys in the numpad, control pad, arrow pad and function sections.

2.1.8. Apple Keyboard Layout

In general, Apple keyboards follow the same layout as PC keyboards, but there are some differences as noted in the following figure.

In this figure, the green keys are those that have been moved to a new location while the blue keys indicate keys that have been added.

2.1.9. Laptop Keyboard Layouts

The limited space available on laptop keyboards often means that the physical key layout needs to be adjusted to fit all the required keys. The writing system keys in the alphanumeric section tend to remain intact, but the other keyboard sections are usually combined with other keys or removed altogether.

In this Apple laptop keyboard, the right control key has been removed to make room for half-height arrow keys and a Fn key is added on the left.

PC laptop keyboards vary considerably, but this sample keyboard demonstrates some commonly found aspects. The control pad keys are added along the right-hand side with the arrow pad keys tucked in along the bottom. The right Shift key is often shrunk to make room for the up arrow key and the right Meta key is typically removed altogether.

2.1.10. Keyboard Layouts For Other Locales

Other locales are not explicitly described in this specification because they start with one of the existing layouts and adapt it by changing the keycaps and the key mappings.

Because these keyboards do not introduce new physical keys, they do not require explicit documentation.

These keyboards are typically based on the "101" (standard or alternate) or "102" layouts. For example, the common Arabic, Cyrillic, Greek, Hindi, Khmer and Thai keyboards are all based on either the "101" or "102" keyboard layouts.

2.2. Mobile Keypads

In the case where a content author wishes to rely on the mechanical layout of a mobile keypad, this specification suggests the keyboard configuration specified in [ISO9995-8], which defines a numeric keypad layout and secondary assignment of Unicode characters in the range U+0061 ... U+007A ("a" - "z") to the number keys 2 through 9, as a common layout appropriate to some international uses.

This keypad layout, and in particular the distribution of letters is for English devices, and will not match the keypads or configurations of many users. Content authors cannot rely upon any particular configuration, and are expected to create content in an internationalized and localizable manner.

2.3. Media Remote Controls

Many keyboards contain special keys to control media functions. Increasingly, many media devices, especially televisions, are Web-enabled. Hybrid keyboard/remote-control devices are becoming more common. To meet the needs of these hybrid Web/media devices, this specification defines keys that are common as remote control buttons, in addition to traditional keyboard keys.

Because of the smaller form factor, keys (or buttons) on a remote control will often be modal, with one key performing different functions based on the context of the on-screen content. Additionally, many keys serve as toggles, to change back and forth between two or more states (see toggling keys). These remote control buttons typically do not have modifier states so each button is assigned a single function (like Play, Pause, Up, Menu or Exit).

2.4. Virtual Keyboards and Chording Keyboards

Virtual keyboards are software-based sets of keys, in a variety of different arrangements, commonly found on touch-screen devices. They are often modal, with the ability to switch between different dynamic sets of keys, such as alphabetic, numeric, or symbolic keys. Because of the lack of physical constraints, these keyboards MAY present the widest range of characters, including emoticons and other symbols. Wherever possible, however, virtual keyboards SHOULD produce the normal range of keyboard events and values, for ease of authoring and compatibility with existing content.

Chording keyboards, also known as chorded keysets or chord keyboards, are key input devices which produce values by pressing several keys in combination or sequence, normally to simulate a full range of characters or commands on a reduced set of keys, often for single-handed use. A chording keyboard MAY have additional mode keys to switch between key values, and the number and type of keys pressed to produce a key value will vary, but the final key values produced by such keyboards SHOULD match the range of key values described in this specification.

For these and other alternative modal keyboards, the key values "Alphanumeric", "CapsLock", "NumLock", and "SymbolLock" are RECOMMENDED for the keys which switch between different modes.

3. Keyboard Event code Value Tables

This section defines a list of values which are appropriate for use as code values.

A key code attribute value is any of the values given in the "KeyboardEvent.code" column of any of the tables in this section of the specification.

Each table in this section has a "Required" column which indicates whether or not the value is required for a conforming implementation. Entries where the "Required" column is "No" are optional and may be used by implementations to support special keyboards (such as multimedia or legacy keyboards).

Note: Some values listed in this specification as "Required" may not be available on all platforms or devices. For example, Mac keyboards do not have an Insert key whereas standard PC keyboards do not have a Help key.

For every key listed as "Required" in this specification, a conforming implementation of the KeyboardEvent interface MUST return the correct value as long as that key is available on that platform.

Note: While every attempt has been made to make this list of values as complete as possible, new values will periodically need to be defined as new input devices are introduced. Rather than allowing user agents to define their own key code attribute values (which are unlikely to be consistent across multiple user agents), bugs SHOULD be filed so that this specification can be updated.

3.1. Alphanumeric Section

The alphanumeric section is the main section of the keyboard. It contains keys that fall into two general categories: writing system keys whose meaning changes based on the current keyboard layout, and functional keys which are (mostly) the same for all layouts.

3.1.1. Writing System Keys

The writing system keys are those that change meaning (i.e., they produce different key values) based on the current locale and keyboard layout.

This figure shows a hypothetical keyboard that combines all the writing system keys (shown in blue and green) found on the various keyboards. Blue keys are present on all standard keyboards while green keys are only available on some keyboards.

The name shown on each key is the code assigned to that key. Wherever possible, the code names are based on the name for the US key in that position (i.e., they are based on the US keyboard layout), which follows the naming convention found in [USB-HID]. For keys that don’t exist on the US keyboard, names from the UK or Japanese layouts are used instead.

Note that there are two "Backslash" keys in this figure: a large one at the end of Row D on the 101-key layout, and a smaller one between "Quote" and "Enter" on Row C of the 102-, 104- and 106-key layouts. Only one "Backslash" key may be present on a keyboard layout.

3.1.2. Functional Keys

The functional keys (not to be confused with the function keys described later) are those keys in the alphanumeric section that provide general editing functions that are common to all locales (like Shift, Tab, Enter and Backspace). With a few exceptions, these keys do not change meaning based on the current keyboard layout.

The "AltRight" key (highlighted in green) is the only functional key that does not generate the same key value for every locale. In some locales it produces "Alt" while in others it produces "AltGraph".

On some keyboards (notably Japanese and Korean) the spacebar is reduced in size to make room for extra keys on the bottom row (Row A). These keys typically allow the users to change the current input mode. Note that even though some of these Japanese and Korean keys occupy the same physical location on the keyboard, they use different code values.

On Apple keyboards, some keys on the bottom row are omitted and others are arranged in a different order.

3.2. Control Pad Section

The control pad section of the keyboard is the set of (usually 6) keys that perform navigating and editing operations, for example, Home, PageUp and Insert.

The code for the Fn key (found on some Apple keyboards) is defined below in the function section.

3.3. Arrow Pad Section

The arrow pad contains the 4 arrow keys. The keys are commonly arranged in an "upside-down T" configuration.

3.4. Numpad Section

The numpad section is the set of keys on the keyboard arranged in a grid like a calculator or mobile phone. This section contains numeric and mathematical operator keys. Often this section will contain a NumLock key which causes the keys to switch between the standard numeric functions and mimicking the keys of the control pad and arrow pad. Laptop computers and compact keyboards will commonly omit these keys to save space.

A keypad is an alternate term for numpad.

The code values in this section should also be used for phone keypads and remote control devices that arrange number keys in a grid.

The standard numpad is sometimes extended with additional keys for parentheses, operators, hexadecimal symbols, or calculator functions (like Backspace). Some of the commonly added keys are listed in the table below.

For numpads that provide keys not listed here, a code value string should be created by starting with "Numpad" and appending an appropriate description of the key.

3.5. Function Section

The function section runs along the top of the keyboard (above the alphanumeric section) and contains the function keys and a few additional special keys (for example, Esc and Print Screen).

A function key is any of the keys labelled F1 ... F12 that an application or operating system can associate with a custom function or action.

On some keyboards (especially those found on laptops or other portable computers), the function keys (F1 ... F12) are defined to have other primary functions (like controlling display brightness or audio volume) and require that a separate Fn key be pressed to make them act as function keys. Unfortunately, the primary functions assigned to these keys varies widely from one manufacturer to the next. Because of this, the code is always set to the function key name.

For keyboards that provide more than 12 function keys, the code value follows the pattern shown above with "F" followed by the function key number - "F13", "F14", "F15", and so on.

Apple keyboards may have Eject or Power keys in the function section. The code values for these keys are defined in § 3.6 Media Keys.

3.6. Media Keys

Media keys are extra keys added to a keyboard that provide media related functionality like play, pause or volume control. These keys do not have a standard location on the keyboard so keyboards from different manufacturers are likely to have a different arrangement of keys or a completely different sets of keys.

Media keys are often distinct from normal typing keys in appearance and may be recessed in the keyboard.

On laptop keyboards, these keys are often merged with the function keys, with the media key interpretation being the primary function of the key and the function key interpretation requiring the Fn key to be pressed at the same time. In this configuration the code should be set to match the function key ("F1" ... "F12"). When the keys are merged in this fashion, the code values are taken from the function key value because the media key value is not consistent across keyboards.

3.7. Legacy, Non-Standard and Special Keys

These keys are not found on modern standard keyboards. They are listed here for reference purposes.

The following keys may be found on non-standard international keyboards.

And finally, the following code value should only be used when the corresponding key does not correspond to any of the code values given elsewhere in this specification. This value is appropriate for use with virtual keyboards that do not have their keys arranged in a way that corresponds to those on a physical keyboard.

Conforming implementations MUST only use "Unidentified" as a key code when there is no way for the implementation to determine the key code. Exposing only this value MUST NOT indicate a conforming implementation.

4. Accessibility

This specification simply defines a set of values that are valid for use in the code attribute. Thus, it does not introduce any features that have accessibility concerns.

The FAST checklist has been completed and nothing is applicable to this specification.

A note related to the FAST checklist item: "If technology provides internationalization support". This specification inherently defines code values for keyboards and provides human-readable names (like "ShiftLeft", "ControlRight", "AltGr" or "KeyQ").

These special key values are defined as human-readable strings so that code to detect special keys can be easier to understand. While these values are not intended to be exposed directly to users, there is nothing preventing that. Apps that choose to expose these values would need to determine whether or not it is appropriate to translate these strings for presentation (e.g.: presenting "Backspace" as "Suppr. arrière" for French users).

5. I18n

The short I18n checklist has been completed and the following item requires a comment:

• "describes a format or data that is likely to need localisation": This specification defines values that are not intended for display to the user, although there is nothing preventing sites from exposing these values.

6. Security Considerations

The Security and Privacy Self-Review Questionairre has been completed with the following notes:

• 2.1 What information might this feature expose to Web sites or other parties, and for what purposes is that exposure necessary?: This spec defines a set of valid values for the code attribute of the various key events. This is necessary to provides a platform-independent way of identifying which physical key (by location) has been pressed (for example, WASD keys in games).

• 2.17 How does your feature handle non-"fully active" documents?: This attribute is only associated with key events, and events are not sent if the document is not fully active.

Security concerns associated with the code attribute are addressed in the [UIEvents] specification.

7. Privacy Considerations

The Security and Privacy Self-Review Questionairre has been completed with the following notes:

• 2.6 Do the features in your specification expose information about the underlying platform to origins?: The code attribute contains a platform-independent "scancode" value for the key pressed by the user. There are a few special `code` values that can be used to identify particular keyboards. For example, `IntlBackslash`, `IntlRo` and `IntlYen`. The user would have to type these keys for the information to be exposed.

• 3.5 Legitimate Misuse: A site could capture all keypresses and build a map of the values generated by the keyboard. If the user types enough values (and doesn’t change keyboard), then the site could try to match those values against a database of known keyboard layouts to guess the user’s current keyboard layout. However, that’s a concern for the key attribute itself (defined in the [UIEvents] specification) rather than something specific to the values defined in this document

Privacy concerns associated with the code attribute are addressed in the [UIEvents] specification.

8. Acknowledgements

Considerable thanks are due to the following participants of the WebApps Working Group for providing substantial material contributions in the process of developing this specification.

Gary Kacmarcik (Google), Masayuki Nakano (Mozilla)