Combobox field

Overview

link

Web

tanrei-combobox-field

schedule

SwiftUI

TanreiComboboxField

radio_button_unchecked

Jetpack Compose

TanreiComboboxField

radio_button_unchecked

Flutter

TanreiComboboxField

radio_button_unchecked

React Native

ComboboxField

radio_button_unchecked

Variants not shipped in

tanrei: filled, outlined

Generated from docs/status/status.json, specs/combobox-field.spec.json

A combobox field that takes one of its options, and one that also takes a value of the person's own

KyotoLisbonNairobiTokyoTorontoInterNoto Sans JPRoboto MonoSource Serif 4

Use a combobox field wherever a form asks for one value that people would rather type than scroll to: a city out of hundreds, a person, a token. It also serves a field that suggests values and takes one of the person’s own, such as a font family. It is the ordinary case, ready to use: a label, the box with its list, a line of help and the words for a wrong value. The box is drawn and measured as the text field’s of the same variant and size, and the list is drawn as a select’s.

Built from a field and a combobox. The field is the frame: the label, the required or optional mark, the help and the error. The combobox is the control: the box, the text typed in it, and the list with its options. The combobox field draws nothing of its own and has no token: every property it has is a property of one of the two, given to it unchanged, and the options you give it are its combobox’s.

It is a block as wide as the place it is put in, and its box fills it. It has no width of its own: for a narrower field, give it a narrower place. Its width never follows its options or its value, because a person types into it before any option is known.

On the web it is <tanrei-combobox-field> with <tanrei-option> children, the elements a select holds. The other platforms have not implemented it yet.

Usage

link

A combobox field holds what its combobox holds, which is two things. value is the committed choice: the chosen option’s value, or a custom text. inputValue is the text in the input. The value changes only when the person chooses an option, commits the text (Enter with no option active, or leaving the field) or presses the clear button; typing and moving through the list never change it.

<form>
  <tanrei-combobox-field name="city" label="City" value="tokyo" required required-text="Required"
    clearable clear-label="Clear city" empty-text="No matches">
    <tanrei-option value="kyoto">Kyoto</tanrei-option>
    <tanrei-option value="tokyo">Tokyo</tanrei-option>
  </tanrei-combobox-field>
</form>

<!-- The box alone, where a label stands elsewhere: a combobox, named by its own label. Importing the combobox field defines it. -->
<tanrei-combobox label="Token" placeholder="Find a token" no-chevron style="inline-size: 16rem">
  <tanrei-option value="primary">primary</tanrei-option>
</tanrei-combobox>

<!-- The options are suggestions: a text that names none becomes the value. -->
<tanrei-combobox-field label="Font family" value="Recursive" allow-custom-value>
  <tanrei-option value="Inter">Inter</tanrei-option>
</tanrei-combobox-field>

<!-- You filter: on input, from a server. The status row says what your source is doing. -->
<tanrei-combobox-field id="assignee" label="Assignee" filter="none" no-chevron placeholder="Find a person">
  <span slot="leading-icon">person_search</span>
</tanrei-combobox-field>

<script type="module">
  import '@tanrei/web/components/combobox-field';

  const assignee = document.querySelector('#assignee');
  // The person changed the text. The combobox does not delay or drop this event: debounce it yourself.
  assignee.addEventListener('input', async () => {
    assignee.status = 'loading';
    assignee.statusText = 'Loading people';
    const people = await find(assignee.inputValue);
    assignee.replaceChildren(...people.map(option));
    assignee.status = 'idle';
    assignee.statusText = `${people.length} of ${total} people shown`;
  });
  // The committed value changed. The value is already the new one.
  assignee.addEventListener('change', (e) => save(e.detail.value));
  // Opened or closed by the person; a close says why. It does not bubble: listen on the field itself.
  assignee.addEventListener('toggle', (e) => console.log(e.detail.open, e.detail.reason));
</script>

import { ComboboxField, Option } from '@tanrei/react';

<ComboboxField label="City" value={city} clearable clearLabel="Clear city" emptyText="No matches" onChange={(event) => setCity(event.detail.value)}>
  <Option value="kyoto">Kyoto</Option>
  <Option value="tokyo">Tokyo</Option>
</ComboboxField>

One level down

link

A combobox field is a field with a combobox in it. Write the two yourself where you need something the field does not offer — something of your own between the label and the box, or below the help. The picture, the name, the description and the states are the same.

<!-- The combobox field -->
<tanrei-combobox-field name="city" label="City" required required-text="Required"
  supporting-text="Where the order is sent." value="tokyo">
  <tanrei-option value="kyoto">Kyoto</tanrei-option>
  <tanrei-option value="tokyo">Tokyo</tanrei-option>
</tanrei-combobox-field>

<!-- The same, by hand: the frame's properties on the field, everything else — and the options — on the combobox -->
<tanrei-field label="City" required required-text="Required" supporting-text="Where the order is sent.">
  <tanrei-combobox name="city" value="tokyo">
    <tanrei-option value="kyoto">Kyoto</tanrei-option>
    <tanrei-option value="tokyo">Tokyo</tanrei-option>
  </tanrei-combobox>
</tanrei-field>

A field with a combobox in it: the same picture as a combobox field

KyotoTokyo

What differs is where the form’s control is: by hand it is the combobox, which takes the name; in the combobox field it is the field.

Specs

link

Groups, supporting text with a disabled option, an error, a read-only and a disabled combobox field

TokyoSeoulLisbonBerlinFreeTeamEnterpriseNairobiTokyoNairobiTokyoNairobiTokyo

The field

link

Part	What it is
Label	The field’s row above the container (stacked), or the combobox’s own label floating inside it (filled, outlined). It is the accessible name, drawn or hidden with labelHidden
Requirement mark	After the label: the requirement tag in its required form, an asterisk or nothing for required; the requirement tag in its optional form for optional. A floating label takes the asterisk
Input	The text: what the person types to find an option and, while they are not typing, the chosen option’s label or the custom value. One line, which scrolls
Placeholder	A hint shown while the input is empty. Never a label, and never a value
Leading icon	The glyph in the leading-icon slot, or else the chosen option’s own
Clear button	With clearable, while the text is not empty: empties the text and the value
Chevron	Says that the field has a list to look through, and opens and closes it. It does not turn. Leave it out (chevron false) where suggestions exist only for what was typed
Supporting text	The field’s row: a line of help. While error is true errorText takes its place (below it, where the design system keeps both). Both start where the input’s text starts

The label row, the mark and the supporting row are the field’s, drawn from the field’s tokens; everything else is the combobox’s. The three variants and the three sizes, small (32), medium (40) and large (56), are the text field’s. The default system ships stacked only.

While the list is open, the label and the help are drawn focused with the box, whether or not the input has focus.

The list

link

The list opens comp.combobox.list.offset below the container, exactly as wide as it, and above it where there is no room below. It is as tall as its rows up to list.max-height (320), and scrolls beyond that.

Part	What it is
Option	A row with a label, and optionally a supporting line and a glyph. The chosen one has a quiet fill and a check
Match	With filter="contains", the part of each label that matched the text is drawn heavier
Group	A run of options under an optional title. A group the filter leaves empty is not drawn
Status row	After the options: statusText, a loading indicator while status is loading, the failure while it is error, or emptyText where nothing matched

filter="contains" shows the options whose label contains the text, whatever the case, the width of a character or the marks on a letter. With filter="none" the combobox shows every option you give it and you filter, on input. The combobox never fetches, waits, sorts or ranks.

Typing, moving and choosing

link

Input	What happens
Typing	Edits the text and opens the list, filtered. The first match is the active option, read out once typing pauses; with allowCustomValue none is
Down Arrow, Up Arrow, list closed; the chevron	Opens the list with every option. The chosen option is the active one, or the first enabled one
Down Arrow, Up Arrow, list open	The next or previous option, across groups, going round at the ends — through the text, where allowCustomValue is set — unless wrap is false
Page Down, Page Up	Ten options down or up
Home, End, Left Arrow, Right Arrow	Move the caret in the text
Enter, an option active; a press on an option	Chooses it and closes the list. It does not submit a form
Enter, no option active	Commits the text, emits action, and submits the form unless action is cancelled
Escape	Closes an open list and keeps the text. Pressed again, restores the committed value’s text. It never clears a value
Tab; a press outside	Leaves the field: the text is resolved and the list closes. The active option is not chosen
A press on the label	Moves focus to the input and opens nothing. While the list is open it is a press outside the combobox: the list closes, and focus stays in the input

Leaving the field resolves the text: the combobox decides which value the text stands for. An empty text empties the value. The whole label of an option chooses that option. Any other text becomes the value with allowCustomValue, and is given up without it.

The list does not open on focus. Set open yourself if you want that.

While an input method is composing, every key belongs to it. The Enter that confirms a conversion chooses nothing and submits nothing.

toggle carries the reason for a close: select, commit, escape, outside, press, tab, focus-out, anchor-hidden or empty.

Anatomy

Anatomy

Drawn over the fixture stacked-empty, as the web package draws it.

Part	Description
1 field	The Field: the label row with its glyph and its requirement mark, and the supporting row with the help and the error text. In a look whose combobox floats the label it draws no label row.
2 combobox	The combobox, as the Field's one control: the box and the text typed in it, the leading glyph, the clear button and the chevron, the list with its options, groups and status row, and the label that floats in the box in the looks that float one.

Properties

Property	Type	Default	Description
variant	stacked | filled | outlined	"stacked"	The text input's three looks, so that a combobox is drawn as the text inputs beside it: stacked is a filled box that shows focus and error with a line inside its edge and draws no label of its own; filled and outlined float the label inside the box. Use one style per form. A design system may leave some out (the Tanrei system ships stacked only) or add values. — Combobox
size	small | medium | large	"medium"	Minimum height of the container: stacked 32 / 40 / 56, as tall as a Button of the same size, so that the box and a Button side by side in one row stand as tall as each other; filled and outlined 40 / 48 / 56, which hold the label that floats inside them. These are the text input's three sizes, small for a bar, a toolbar or a dense row of controls. The hit area always meets the minimum target. A design system may add values. — Combobox
value	string	""	The committed choice: the chosen option's value, or, with allowCustomValue, a text the person typed that names no option. Empty while nothing is chosen. It is one string, for ever: several values are another component. — Combobox Held by the combobox, which changes it by a choice, a commit or the clear button; the combobox field's is the same at every moment (CBF-3).
inputValue	string	""	The text in the input. The combobox writes it as the person types and when a value is chosen or restored; the product may set it, and reads it from input to load options. — Combobox Held by the combobox, which writes it as the person types and when a value is chosen or restored; the combobox field's is the same at every moment (CBF-3).
label	string	""	Names the control, visibly and to assistive technology. Required, unless the control names itself (a checkbox or a switch with its own label): then leave it empty and the field adds only help and an error. — Field Names the combobox. In a filled or outlined look the combobox draws it, floating in its box, and the Field draws no label row (FLD-25, CMB-8).
labelHidden	boolean	false	Does not draw the label, which stays the accessible name. For a control whose visible label is elsewhere (a table column, a toolbar). — Field Hides the label wherever it would be drawn: the Field's row, or the combobox's floating label (FLD-25).
placeholder	string	""	A hint shown while the input is empty and no label is in the input line. Never a replacement for a name. — Combobox
supportingText	string	""	Help shown below the control and given to assistive technology as the control's description. While the field is in error it gives way to errorText, unless the design system keeps both (comp.field.error-text.placement append). — Field
errorText	string	""	Shown while error is true, in supportingText's place — or below it, which then stays, where the design system's comp.field.error-text.placement is append: what is wrong and how to put it right, in words. — Field
error	boolean	false	Puts the field in the error condition: the error text is drawn, the control is exposed as invalid and, where it has an error condition of its own, drawn in it. What a value means is the product's to validate; the field never sets this itself. — Field Puts the Field in its error condition, which puts the combobox in its own (FLD-8, CMB-10).
disabled	boolean	false	Disables the control and draws the frame as disabled. Disable a framed control here, not on the control, so that its label follows. — Field Disables the Field, which disables the combobox (FLD-14, CMB-46).
readOnly	boolean	false	The value is shown, can be focused, selected and copied, and is submitted, but cannot be changed: the list does not open and neither the chevron nor the clear button is drawn. — Combobox
required	boolean	false	What the form asks of the control: true exposes it as required and draws the required mark beside the label. It never validates: a missing answer is the product's to report with error. — Field
optional	boolean	false	Draws the optional tag after the label and adds optionalText to the control's description, because assistive technology has no state for it. Ignored while required is true: a control is never both. — Field
requiredMark	auto | tag | asterisk | none	"auto"	How this control shows that it is required: tag is a small filled Tag with requiredText, asterisk is "*" after the label, none draws nothing and keeps the semantics. Auto takes comp.field.requirement.mark, which follows sys.behavior.requirement-mark, the system's one answer. Ignored unless required is true. — Field
requiredText	string	""	The text of the required tag, in the product's language ("Required", "必須"). The product's: Tanrei has no word for it. Empty reads the product's words; with neither, FLD-24 says what is drawn. — Field
optionalText	string	""	The text of the optional tag, in the product's language ("Optional", "任意"); also read to assistive technology as part of the description. The product's: Tanrei has no word for it. Empty reads the product's words. — Field
open	boolean	false	Whether the list is shown. The combobox opens and closes itself and emits toggle; the product may also set it (to open on focus, for one). Ignored while the combobox is disabled or read-only or has nothing to show. — Combobox Held by the combobox, which opens and closes its list itself; the combobox field's is the same at every moment (CBF-3).
allowCustomValue	boolean	false	False: the value is always one of the options, and a text that names none is given up when the person leaves. True: the options are suggestions, and a text that names none becomes the value as typed (a font family, a tag, an address). — Combobox
filter	contains | none	"contains"	Who decides which options answer the text. contains: the combobox shows the options whose label contains what was typed, ignoring case, and marks the match. none: the combobox shows every option it is given and the product filters — on input, from its own data or a server — and says what it is doing with status. — Combobox
wrap	boolean	true	Whether the arrow keys go round at the ends of the list: Down Arrow on the last option to the first, Up Arrow on the first to the last — with allowCustomValue true, through the text itself, where no option is active (CMB-26). False stops them at the ends. — Combobox
chevron	boolean	true	Draws the chevron that opens the whole list without typing. False for a field whose suggestions exist only for what was typed (a remote search): there is no list to look through. — Combobox
clearable	boolean	false	Draws a clear button while the text is not empty, for a combobox whose value may be none. Without it, emptying the text and leaving the field clears the value. — Combobox
clearLabel	string	""	The clear button's accessible name, in the product's language ("Clear"). Required while clearable is true. — Combobox
status	idle | loading | error	"idle"	What the product's source of options is doing, which the product sets: idle (the options given are final), loading (options are on their way: the status row shows a loading indicator), error (the source failed: the status row shows statusText in the error color). — Combobox
statusText	string	""	The status row's text, in the product's language, announced to assistive technology when it changes: a count ("12 of 340 shown"), that loading failed, or, while status is loading, the loading indicator's name ("Loading options"). — Combobox
emptyText	string	""	Shown in the list while the text names nothing the combobox can show, allowCustomValue is false and no status is set, in the product's language ("No matches"). The product's: Tanrei has no words for it. Empty reads the product's words; with neither, no such row is drawn and it is reported (CMB-32). — Combobox
separation	auto | divider | gap	"auto"	How a group of options is told from what is next to it. divider: a line between them. gap: empty space and no line. Auto takes comp.combobox.separation, which follows the design system's choice. — Combobox
iconSpace	auto | always | never	"auto"	Whether a shown option keeps the room of the leading icon column where it has no icon, so that the labels of a section start on one line — a section being the shown options of a group, or a run of adjacent shown options outside any group. auto: an option keeps the column while another shown option of its section has a leading icon; an option the filter hides does not count. always: every option keeps it. never: only an option that has an icon has the column. The menu's and the select's iconSpace, with the same values and default (CMB-67). — Combobox
density	regular | compact	"regular"	How much room an option of the list takes: its least height, its paddings, the gap between its columns and the size of its glyphs (the leading icon, the check), and never its text style. regular (a 48 row in the default system) is for a product used by touch as well as by pointer; compact (a 32 row with 20 glyphs, the menu's compact row) is for a tool used with a pointer, whose lists are long. For touch an option is never lower than the touch target in either (CMB-34). The field's own box is not changed: its height is size's. A design system may add values. — Combobox

Slots

Slot	Description
leading-icon	A glyph at the start of the container that stands for the combobox whatever is chosen (a magnifier before a field that searches people). It takes the place of the chosen option's own glyph. — Combobox
label-icon	A glyph before the label. — Field

Events

Event	Description
input	The person changed the text (typing, deleting, pasting, dictating, the clear button, Escape restoring it); carries the new text. Not emitted when the product sets inputValue or value, or when a choice writes its label. It is the product's cue to load options; the combobox does not delay or drop it. — Combobox
change	The committed value changed by the person: an option was chosen, a custom text was committed, or the value was cleared; carries the new value and the text now shown. Not emitted when the product sets value, when the chosen option is chosen again, or while the person only types or moves through the list. — Combobox
toggle	The list was opened or closed by the person or by having nothing left to show; carries the new open and, for a close, the reason: select, commit, escape, back, outside, press, tab, focus-out, anchor-hidden or empty (in the platform's casing). After a choice it follows change. — Combobox
action	The person pressed Enter with no option active and the text was committed; emitted after any change it caused. On the web it is followed by the form's submission unless cancelled. — Combobox

Items

The kinds of item the component repeats. A fixture lists its items in order; each platform names each kind in its own idiom.

option

One choice of the combobox: a label, the value it stands for, and optionally a supporting line and a glyph. The same kind a select holds.

Property	Type	Default	Description
label	string	""	The option's text and its accessible name: what the filter searches and what the input shows once the option is chosen. Required.
value	string	""	Identifies the choice: the option is the chosen one while the combobox's value equals it. Unique within the combobox and not empty: the empty value means that nothing is chosen.
supportingText	string	""	A line below the label that says more about the choice. Shown in the list, not in the input; not searched.
leadingIcon	string	""	The name of an icon (a glyph of the system's icon set) before the label; the container shows it too while the option is chosen and the combobox has no leading icon of its own.
disabled	boolean	false	Prevents the option from being chosen. It stays reachable with the arrow keys.

Spec	Web	SwiftUI	Jetpack Compose	Flutter	React Native
Item	tanrei-option	TanreiComboboxOption	TanreiComboboxOption	TanreiComboboxOption	ComboboxOption
label · Property	label	title	text	label	label
value · Property	value	tag	value	value	value
supportingText · Property	supportingText	supportingText	supportingText	supportingText	supportingText
leadingIcon · Property	leadingIcon	leadingIcon	leadingIcon	leadingIcon	leadingIcon
disabled · Property	disabled	disabled	enabled	enabled	disabled
Notes	<tanrei-option value="tokyo">Tokyo</tanrei-option>: the element a select holds, and the same data: the label is the label attribute or, without one, the element's text. Attributes supporting-text, leading-icon, disabled. It draws nothing itself. tanrei-option and tanrei-option-group are one pair of elements for the select and the combobox, defined once; an option with the empty value is refused by the combobox (CMB-17, CMB-57), not by the element, because a select allows it.	TanreiComboboxOption(_ title:, supportingText:, leadingIcon:).tag(value); disabled follows .disabled(_:).	TanreiComboboxOption(text, value, supportingText, leadingIcon, enabled), called in the combobox's content lambda.	TanreiComboboxOption<String>(value:, label:, supportingText:, leadingIcon:, enabled:), in the combobox's options list, as DropdownMenuEntry.	{ label, value, supportingText?, leadingIcon?, disabled? }: an element of the options array.

option-group · group — holds items

A run of related options, optionally titled. The combobox separates a group from what is next to it by a divider or a gap, and draws neither a group nor its title while the filter leaves it empty.

Property	Type	Default	Description
title	string	""	A short heading drawn above the group's options, which also names the group; empty draws none and leaves the group unnamed.

Spec	Web	SwiftUI	Jetpack Compose	Flutter	React Native
Item	tanrei-option-group	TanreiComboboxSection	TanreiComboboxGroup	TanreiComboboxGroup	ComboboxOptionGroup
title · Property	label	title	title	title	title
Notes	The title is the label attribute, as <optgroup label>: a title attribute would also draw the browser's tooltip.	TanreiComboboxSection(_ title:) { … }, as Section.	TanreiComboboxGroup(title) { … }.	TanreiComboboxGroup(title:, options: […]), in the same list.	{ kind: 'group', title?, options: ComboboxOption[] } in the same array.

States

Behavior

Requirements in EARS form. Every platform implementation is tested against these ids.

ID	Requirement
CBF-1	THE combobox field SHALL be a Field that frames one combobox, and nothing else. It SHALL give label, labelHidden, supportingText, errorText, error, disabled, required, optional, requiredMark, requiredText and optionalText to its Field and every other prop to its combobox, each unchanged; SHALL hold the label-icon slot for its Field and the leading-icon slot for its combobox; SHALL give its options to its combobox (CBF-2); and SHALL emit its combobox's events as its own, each once. THE combobox field SHALL be as wide as the place it stands in, and its combobox SHALL fill it: it is a block with no width of its own, as its Field is (FLD-1), around a control that fills the width it is given (CMB-49). It SHALL draw no part of its own and have no token of its own: what it shows, how it behaves and what it exposes to assistive technology SHALL be exactly what that Field and that combobox do when a product places the one in the other (FLD-1 to FLD-28; CMB-1 to CMB-62) — the label row and its requirement mark (FLD-2 to FLD-6), or the label that floats in the box with the Field's row left out (FLD-25, CMB-7, CMB-8); the supporting row and the error (FLD-7 to FLD-9, FLD-26, CMB-10); the name, the description and the states (FLD-10, FLD-11, FLD-14, CMB-12, CMB-46); and the list, which is the combobox's alone and as wide as its container (CMB-22).
CBF-2	THE combobox field SHALL take the options and the option groups a product gives it — in the platform's form for a combobox's own (its child elements on the web) — and give them to its combobox as that combobox's options, in the order given, each with its label, its value, its supporting text, its leading icon and its disabled, and each group with its title: the option a product wrote SHALL be the option its combobox reads, never a copy of it. THE combobox field SHALL NOT read, filter, order, count or keep an option, and SHALL make no option active or chosen: which options are shown, which is active and which is the chosen one are its combobox's (CMB-25, CMB-26, CMB-36). WHEN the product adds, removes, reorders or changes an option or a group THE combobox field's combobox SHALL meet the change at once and as CMB-31 says, as though the product had changed that combobox's own options.
CBF-3	THE combobox field SHALL hold no value, no text and no open state of its own: its value, its inputValue and its open SHALL at every moment be its combobox's. WHEN its combobox changes one of them — a choice, a commit or the clear button (CMB-17, CMB-20, CMB-27 to CMB-29); typing, or a text the combobox writes itself for a choice, for a commit that was given up or for Escape (CMB-16, CMB-27, CMB-29, CMB-30); the list opening or closing, or open taken back because there is nothing to show (CMB-21, CMB-30, CMB-57) — THE combobox field's SHALL be the new one before any event that reports the change is emitted, and equally WHERE no event reports it. WHEN the product sets one on the combobox field THE combobox field SHALL set it on its combobox and nothing else, so that no event follows (CMB-31).
CBF-4	WHERE the platform has forms (the web) THE combobox field SHALL be the one control the form sees: it SHALL take name, submit its combobox's value — never the text of an edit that was not committed — reset to the value it was first given, restore it on navigation, report to the form's constraint validation exactly what its combobox would report there (CMB-59), and be left out WHILE disabled is true or a disabled group of the form holds it; its combobox and its Field SHALL take no part in the form themselves. WHEN Enter asks for the form's submission (CMB-28) the form asked SHALL be the combobox field's own, through that form's default button (BTN-30), and not WHEN action was cancelled.
CBF-5	WHEN the combobox field is given focus — by the product, by a press on any part of it that FLD-12 or CMB-14 gives to the input, or by a form that reports its validity — THE combobox field SHALL pass the focus to its combobox's input and SHALL add no stop to the focus order: the stops inside it are its combobox's, in that combobox's order (the input, then the clear button while it is shown). WHILE focus is anywhere inside it, or its combobox's list is open, its Field's rows SHALL be drawn focused, because its combobox says so to its Field (FLD-13, CMB-61): the combobox field arranges nothing for it. A press on its Field's label row WHILE the list is open is a press outside the combobox: the list SHALL close with the reason outside, choosing nothing (CMB-30), and focus SHALL go to the input (FLD-12).
CBF-6	IF the combobox field is placed in a Field THE combobox field SHALL in debug builds report that it is a field already and that the bare control is the combobox, and both SHALL still render (FLD-15). WHILE it stands in a field group THE combobox field SHALL follow that group's disabled, through its own Field, and take nothing else from the group (FGR-20).
CBF-7	THE combobox field SHALL have no words of its own and SHALL read none: requiredText and optionalText are read by its Field (FLD-24), emptyText and clearLabel by its combobox (CMB-60), each from the instance's prop and then from the product's words.
CBF-8	WHERE the platform has ARIA attributes (the web), WHEN the product sets an aria- attribute on the host, by the attribute or by the ARIA property that reflects it, THE combobox field SHALL move it to the data-aria- attribute of the same name, so that the host is no second node with its name, description or state, and SHALL expose it on the element that carries its role — an id reference by the elements it names in the host's tree or a tree around it, an error message as part of the description while the combobox field is invalid — except those the combobox field owns (aria-label, aria-labelledby, aria-disabled, aria-haspopup, aria-expanded, aria-controls), which it SHALL move and not expose: its name is label (CBF-1). WHEN the product removes the aria- attribute or its data-aria- twin, or sets the ARIA property that reflects it (ariaLabel, ariaDescribedByElements…) to null, THE combobox field SHALL take it off that element. WHEN the product sets an aria- attribute the combobox field owns THE combobox field SHALL report it in debug builds.

Platform name mapping

Parity does not mean identical APIs. Each platform uses its own idiom for the same contract.

Spec	Web	SwiftUI	Jetpack Compose	Flutter	React Native
Component	tanrei-combobox-field	TanreiComboboxField	TanreiComboboxField	TanreiComboboxField	ComboboxField
variant · Property	variant	variant	variant	variant	variant
size · Property	size	size	size	size	size
value · Property	value	selection	value	value	value
inputValue · Property	inputValue	text	inputValue	controller	inputValue
label · Property	label	label	label	labelText	label
labelHidden · Property	labelHidden	labelsHidden	labelHidden	labelHidden	labelHidden
placeholder · Property	placeholder	prompt	placeholder	hintText	placeholder
supportingText · Property	supportingText	supportingText	supportingText	helperText	supportingText
errorText · Property	errorText	errorText	errorText	errorText	errorText
error · Property	error	error	isError	isError	error
disabled · Property	disabled	disabled	enabled	enabled	disabled
readOnly · Property	readOnly	readOnly	readOnly	readOnly	readOnly
required · Property	required	isRequired	required	required	required
optional · Property	optional	isOptional	optional	optional	optional
requiredMark · Property	requiredMark	requiredMark	requiredMark	requiredMark	requiredMark
requiredText · Property	requiredText	requiredText	requiredText	requiredText	requiredText
optionalText · Property	optionalText	optionalText	optionalText	optionalText	optionalText
open · Property	open	isPresented	expanded	menuController	open
allowCustomValue · Property	allowCustomValue	allowCustomValue	allowCustomValue	allowCustomValue	allowCustomValue
filter · Property	filter	filter	filter	filter	filter
wrap · Property	wrap	wrap	wrap	wrap	wrap
chevron · Property	noChevron	chevron	chevron	chevron	chevron
clearable · Property	clearable	clearable	clearable	clearable	clearable
clearLabel · Property	clearLabel	clearLabel	clearContentDescription	clearSemanticLabel	clearAccessibilityLabel
status · Property	status	status	status	status	status
statusText · Property	statusText	statusText	statusText	statusText	statusText
emptyText · Property	emptyText	emptyText	emptyText	emptyText	emptyText
separation · Property	separation	separation	separation	separation	separation
iconSpace · Property	iconSpace	iconSpace	iconSpace	iconSpace	iconSpace
density · Property	density	density	density	density	density
input · Event	input	text	onInputValueChange	onInputChanged	onInputValueChange
change · Event	change	selection	onValueChange	onChanged	onValueChange
toggle · Event	toggle	isPresented	onExpandedChange	onOpenChanged	onOpenChange
action · Event	action	onSubmit	keyboardActions	onSubmitted	onSubmitEditing
Notes	The tag tanrei-combobox-field, the class TanreiComboboxField, the React name ComboboxField. It takes the combobox's attributes, children and listeners and the Field's, name for name. The element is composed as every composed element on the web is (the web package's README, Composed elements); what follows is what is particular to it, and the three places where this element needs more than every composed element has. Members: <tanrei-field> holding one <tanrei-combobox> in its default slot; the product places no member. The host is display: block. Value member: tanrei-combobox. The host is the form's element — name, the value and its state, validity anchored on the combobox's input, reset to the value attribute, restore, form, a disabled fieldset — and the combobox inside has no name. Props, set as properties on the member each is from. On the Field: label, labelHidden, supportingText, errorText, error, disabled, required, optional, requiredMark, requiredText, optionalText. On the combobox: variant, size, value, inputValue, placeholder, readOnly, open, allowCustomValue, filter, noChevron (the inverse of chevron, attribute no-chevron), clearable, clearLabel, status, statusText, emptyText, separation. Attributes are the members' own: kebab-case, except readonly. Props of one name on both members — label, labelHidden, error, disabled — are the Field's; the combobox's are never set by the element and reach the combobox through the connection. **1. Three props the member writes** (a composed element sets each prop on its member, with one exception, the value, which it reads back on the member's event): the combobox writes value, inputValue and open itself, and writes the text with no event when a commit is given up (CMB-29). The host therefore keeps no copy of the three: each is an accessor over the member's property — a get reads the member's, a set writes the member's, and a value set before the member exists is kept and given at its first render — so that event.target.value, .inputValue and .open are the new ones in every listener and between events (CBF-3). open reflects on the host as it does on the member: the host writes its own attribute when the member tells it of an update, by the primitive through which the member already tells the host its form value. **2. The options are passed by the default slot** (other passed-on children use named slots): the shadow root is <tanrei-field><slot name="label-icon" slot="label-icon"></slot><tanrei-combobox><slot></slot><slot name="leading-icon" slot="leading-icon"></slot></tanrei-combobox></tanrei-field>. The product's <tanrei-option> and <tanrei-option-group> children stay the host's light-DOM children and are assigned to the unnamed <slot>, which is a child of the combobox; the combobox reads a <slot> among its children as the elements assigned to it and reads again on slotchange and on a change of an assigned element (primitives/option-list.ts, the combobox's web note; the select reads its options the same way, with the same reader). Unlike a passing named slot, the unnamed one is always rendered: the combobox draws no room for options, so an empty slot is no option. The host never reads its option children. Slots: label-icon is passed to the Field and leading-icon to the combobox, each by a slot element of the same name rendered only while the host has a child for it. **3. A forwarded attribute that is no prop**: inline, the combobox's web-only attribute that draws an open list in place for the fixtures, is forwarded as a property, and select() is passed on as focus() and blur() are. Events: input is the native, composed event of the text element, and change and action are the combobox's own composed, bubbling events; the three leave by themselves, with the host as their target, and action stays cancelable. toggle is composed and does not bubble: it is heard on the host, as on any shadow host, and by no ancestor — which needs the combobox's toggle to be composed, as it is not today (the combobox's web note). None is stopped and none is copied. Parts: the member hosts are field and combobox. Exported from the Field: label, label-icon, requirement-label, supporting-text. Exported from the combobox: container, outline, active-indicator, label, requirement-label, input, leading-icon, clear-button, chevron, list, option, option-label, option-supporting-text, option-leading-icon, mark, group, group-title, divider, status. Two names collide, label and requirement-label. Each is exported with its member's name before it, always (field-label, combobox-label, field-requirement-label, combobox-requirement-label), and under the bare name from both members as well, because the two are one thing to a person and are never drawn at once: FLD-25 is the sentence that holds it. Focus: the shadow root does not delegate. focus(), blur() and select() call the combobox's; a press on the label row focuses the input by FLD-12, a press on the box by CMB-14, and a press on the help does nothing. The combobox's list is a popover of the combobox's own shadow root, in the top layer; the combobox is its opener, so a press on the Field's rows while it is open is a press outside (CBF-5). The connection is the Field's with its control, with one value more upward, that the control is drawn focused (FLD-13, FLD-25, FLD-26, CMB-61); the element takes no part in it. Parts and tokens of its own: none. The element writes no custom property: --tanrei-comp-field-*, --tanrei-comp-input-box-* and --tanrei-comp-combobox-* reach the members by inheritance, and one combobox field is set apart by setting any of them on the element. What its twin cannot do that it does: nothing. The twin: <tanrei-field label="City" supporting-text="Where the order is sent." required><tanrei-combobox name="city" value="tokyo"><tanrei-option value="kyoto">Kyoto</tanrei-option><tanrei-option value="tokyo">Tokyo</tanrei-option></tanrei-combobox></tanrei-field>. Before the element is defined its options are running text: a page hides them with tanrei-combobox-field:not(:defined) > * { display: none } and gives the tag a block size. Words: none of its own; required-text and optional-text are read by the Field, empty-text and clear-label by the combobox.	TanreiComboboxField("City", selection: $city, text: $query) { TanreiComboboxOption("Tokyo").tag("tokyo") … }: a view built from TanreiField and TanreiCombobox, with the combobox's two bindings and its content builder passed through and the Field's arguments beside them. It takes TanreiCombobox's arguments, name for name. One instance is set apart by .tanreiTheme(_:) on the view. The options are TanreiComboboxOption and TanreiComboboxSection, the combobox's own. Planned, after the Field and the combobox.	TanreiComboboxField(value, onValueChange, label = "City") { TanreiComboboxOption("Tokyo", "tokyo") … }: a composable that calls TanreiField with TanreiCombobox as its content and passes the content lambda through. enabled is the inverse flag and isError keeps Compose's name. One instance is set apart by TanreiTheme(…) { } around it. Planned, after the Field and the combobox.	TanreiComboboxField(value:, onChanged:, labelText:, helperText:, errorText:, options: […]): a widget that builds TanreiField around TanreiCombobox and passes options through; labelText, hintText, helperText, errorText and enabled keep InputDecoration's names, enabled the inverse flag. TanreiComboboxFormField wraps the combobox field as a FormField<String>. One instance is set apart by a TanreiTheme around it. Planned, after the Field and the combobox.	<ComboboxField label="City" supportingText="Where the order is sent." value={city} onValueChange={setCity} options={[…]} />: a component that renders Field around Combobox and passes options through as given. inputValue / onInputValueChange and open / onOpenChange are the combobox's optional pairs. One instance is set apart by a provider around it. Planned, after the Field and the combobox.

Tokens

Token	Aliases	Resolved (light)
--tanrei-comp-field-counter-gap	sys.space.space200	16px
--tanrei-comp-field-error-text-gap	sys.space.space50	4px
--tanrei-comp-field-error-text-placement	—	0
--tanrei-comp-field-label-icon-gap	sys.space.space100	8px
--tanrei-comp-field-label-icon-size	sys.icon.small	20px
--tanrei-comp-field-label-gap	sys.space.space100	8px
--tanrei-comp-field-motion-state-duration	sys.motion.role.state.default	250ms
--tanrei-comp-field-motion-state-easing	sys.motion.easing.state	cubic-bezier(0.2, 0, 0, 1)
--tanrei-comp-field-requirement-asterisk-gap	sys.space.space25	2px
--tanrei-comp-field-requirement-gap	sys.space.space100	8px
--tanrei-comp-field-requirement-mark	sys.behavior.requirement-mark	0
--tanrei-comp-field-standard-counter-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-disabled-counter-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-text-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-counter-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-label-icon-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-label-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-required-asterisk-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-supporting-text-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-error-value-text-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-label-icon-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-label-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-required-asterisk-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-supporting-text-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-disabled-value-text-color	—	#1b1b1b · 38%
--tanrei-comp-field-standard-error-text-color	sys.color.error	#cd262f
--tanrei-comp-field-standard-error-counter-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-error-label-icon-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-error-label-color	sys.color.on-surface	#1b1b1b
--tanrei-comp-field-standard-error-required-asterisk-color	sys.color.primary	#1b1b1b
--tanrei-comp-field-standard-error-supporting-text-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-error-value-text-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-focused-counter-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-error-text-color	—	#cd262f
--tanrei-comp-field-standard-focused-error-counter-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-error-label-icon-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-error-label-color	—	#1b1b1b
--tanrei-comp-field-standard-focused-error-required-asterisk-color	—	#1b1b1b
--tanrei-comp-field-standard-focused-error-supporting-text-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-error-value-text-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-label-icon-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-label-color	—	#1b1b1b
--tanrei-comp-field-standard-focused-required-asterisk-color	—	#1b1b1b
--tanrei-comp-field-standard-focused-supporting-text-color	—	#4b4b4b
--tanrei-comp-field-standard-focused-value-text-color	—	#4b4b4b
--tanrei-comp-field-standard-label-icon-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-label-color	sys.color.on-surface	#1b1b1b
--tanrei-comp-field-standard-required-asterisk-color	sys.color.primary	#1b1b1b
--tanrei-comp-field-standard-supporting-text-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-standard-value-text-color	sys.color.on-surface-variant	#4b4b4b
--tanrei-comp-field-supporting-text-gap	sys.space.space50	4px
--tanrei-comp-field-value-text-gap	sys.space.space200	16px
--tanrei-comp-field-label-typescale	sys.typescale.label	500 14px/1.4286
--tanrei-comp-field-supporting-text-typescale	sys.typescale.label-small	500 12px/1.3333
--tanrei-comp-field-value-text-typescale	sys.typescale.label	500 14px/1.4286

Fixtures

Canonical renderings. Every platform snapshots each fixture under the same id so the results can be compared.

variant: stacked (46)

stacked-empty

variant: stacked label: City items: 5

stacked-value

variant: stacked value: tokyo label: City items: 5

stacked-open

variant: stacked value: tokyo label: City open: true items: 5 Drawn alone in a window of 312 × 472

stacked-large

variant: stacked size: large value: tokyo label: City items: 5

stacked-error

variant: stacked label: City errorText: Choose the city you are sending to. error: true items: 5

stacked-disabled

variant: stacked value: tokyo label: City disabled: true items: 5

stacked-placeholder

label: City placeholder: Type to find a city items: 5

stacked-label-hidden

value: tokyo label: City labelHidden: true items: 5

stacked-supporting

value: tokyo label: City supportingText: Where the order is sent. items: 5

stacked-error-value

value: nairobi label: City supportingText: Where the order is sent. errorText: We do not deliver to Nairobi yet. error: true items: 5

stacked-read-only

value: tokyo label: City readOnly: true items: 5

stacked-clearable

value: tokyo label: City clearable: true clearLabel: Clear city items: 5

stacked-no-chevron

label: Address placeholder: Start typing an address filter: none chevron: false items: 1

stacked-custom-value

value: Recursive label: Font family allowCustomValue: true items: 4

stacked-required

label: City required: true requiredText: Required items: 5

stacked-optional

label: City optional: true optionalText: Optional items: 5

stacked-required-asterisk

label: City required: true requiredMark: asterisk items: 5

stacked-required-error

label: City errorText: Choose the city you are sending to. error: true required: true requiredText: Required items: 5

stacked-required-disabled

value: tokyo label: City disabled: true required: true requiredText: Required items: 5

stacked-label-icon

value: tokyo label: City items: 5 slots: label-icon

stacked-leading-icon

label: Assignee placeholder: Find a person items: 2 slots: leading-icon

stacked-option-icon

value: train label: Transport items: 3

open-none-chosen

label: City open: true items: 5 Drawn alone in a window of 312 × 473

open-filtered

value: tokyo inputValue: to label: City open: true items: 5 Drawn alone in a window of 312 × 473

open-filtered-none

inputValue: zz label: City open: true emptyText: No matches items: 5 Drawn alone in a window of 312 × 473

open-icons

value: train label: Transport open: true items: 3 Drawn alone in a window of 312 × 473

open-supporting-text

value: sys.color.on-primary inputValue: primary label: Token open: true items: 4 Drawn alone in a window of 312 × 473

open-disabled-chosen

value: sys.color.secondary label: Token open: true items: 4 Drawn alone in a window of 312 × 473

open-groups

value: Europe/Lisbon label: Time zone open: true items: 3 Drawn alone in a window of 312 × 473

open-groups-divider

value: Europe/Lisbon label: Time zone open: true separation: divider items: 3 Drawn alone in a window of 312 × 473

open-groups-gap

value: Europe/Lisbon label: Time zone open: true separation: gap items: 3 Drawn alone in a window of 312 × 473

open-groups-filtered

inputValue: in label: Time zone open: true items: 3 Drawn alone in a window of 312 × 473

open-many

value: lisbon label: City open: true items: 24 Drawn alone in a window of 312 × 473

open-long-options

label: Licence open: true items: 2 Drawn alone in a window of 312 × 473

open-custom-suggestions

inputValue: no label: Font family open: true allowCustomValue: true items: 4 Drawn alone in a window of 312 × 473

open-loading

inputValue: ai label: Assignee open: true filter: none chevron: false status: loading statusText: Loading people items: 1 Drawn alone in a window of 312 × 473

open-status

inputValue: a label: Assignee open: true filter: none chevron: false statusText: 2 of 48 people shown. Keep typing to nar… items: 2 Drawn alone in a window of 312 × 473

open-status-error

inputValue: ai label: Assignee open: true filter: none chevron: false status: error statusText: People could not be loaded. Check your c… items: 1 Drawn alone in a window of 312 × 473

long-value

value: cc-by-nc-sa label: Licence items: 2

long-label

label: Which of the cities we deliver to is nea… supportingText: If none of them is near enough, leave th… required: true requiredText: Required items: 5

stacked-required-ja

value: kyoto label: 都市 required: true requiredText: 必須 items: 3

open-filtered-ja

inputValue: 京 label: 都市 optional: true optionalText: 任意 open: true emptyText: 一致する項目がありません items: 3 Drawn alone in a window of 312 × 473

stacked-required-rtl

value: cairo label: المدينة supportingText: إلى أين نرسل الطلب. required: true requiredText: مطلوب clearable: true clearLabel: مسح المدينة direction: rtl items: 2 slots: label-icon

open-rtl

value: Asia/Riyadh inputValue: ال label: المنطقة الزمنية open: true direction: rtl items: 2 Drawn alone in a window of 312 × 473

long-value-rtl

value: cc-by-nc-sa label: רישיון direction: rtl items: 2

stacked-error-rtl

label: עיר errorText: יש לבחור עיר מהרשימה. error: true optional: true optionalText: רשות direction: rtl items: 2

variant: filled (6)

filled-empty

variant: filled label: City items: 5

filled-value

variant: filled value: tokyo label: City items: 5

filled-open

variant: filled value: tokyo label: City open: true items: 5 Drawn alone in a window of 312 × 473

filled-large

variant: filled size: large value: tokyo label: City items: 5

filled-error

variant: filled label: City errorText: Choose the city you are sending to. error: true items: 5

filled-disabled

variant: filled value: tokyo label: City disabled: true items: 5

variant: outlined (8)

outlined-empty

variant: outlined label: City items: 5

outlined-value

variant: outlined value: tokyo label: City items: 5

outlined-open

variant: outlined value: tokyo label: City open: true items: 5 Drawn alone in a window of 312 × 473

outlined-large

variant: outlined size: large value: tokyo label: City items: 5

outlined-error

variant: outlined label: City errorText: Choose the city you are sending to. error: true items: 5

outlined-disabled

variant: outlined value: tokyo label: City disabled: true items: 5

outlined-required

variant: outlined label: City required: true requiredText: Required items: 5

outlined-rtl

variant: outlined value: cairo label: المدينة direction: rtl items: 2

Generated from specs/combobox-field.spec.json, tokens/comp/field.tokens.json, design/tokens/

What the web draws differently

link

• <tanrei-option> and <tanrei-option-group> are data: they draw nothing. They are the elements a select holds. An option whose value is the empty string is drawn and cannot be chosen, because the empty value means that nothing is chosen.
• The element’s shadow root holds a <tanrei-field> around a <tanrei-combobox>. Your <tanrei-option> children stay its own children and reach the combobox through a slot; nothing is moved or copied.
• The combobox field is a form-associated element: the one control the form sees. It takes name, submits value and never the text of an edit that was not committed, resets to the value attribute, and reports a missing value to the form while required and value is empty. Enter with no option active submits its form.
• value, inputValue and open are the combobox’s at every moment: each is already the new one in every listener.
• chevron and wrap are the inverse attributes no-chevron and no-wrap, and readOnly is readonly.
• input is the native event of the text element. change and action carry detail.value and detail.inputValue. The four events are the combobox’s own, with the combobox field as their target; toggle does not bubble.
• focus() goes to the input. The element itself is not focusable and has no role: name it with label, never with aria-label.
• Parts: field and combobox are the two members; each member’s parts are exported under their own names, and label and requirement-label also as field-label, combobox-label, field-requirement-label and combobox-requirement-label.
• One field is set apart by a custom property on it: --tanrei-comp-field-* for the rows, --tanrei-comp-input-box-* for the box, --tanrei-comp-combobox-* for the list.
• The list is a popover="manual" element in the top layer. A press outside closes it and also reaches the element under it.
• The status row stands under the options and does not scroll with them, so a count or a failure stays in view.
• Before the element is defined, its options are running text. Hide tanrei-combobox-field:not(:defined) > * and reserve the height.
• The web has no back gesture of its own, so toggle never carries the reason back.

Guidelines

link

Combobox field, select, search or a text field

link

Aspect	Combobox field	Select	Search	Text field
Holds	One value found by typing	One value of a closed list	A query	Any text
Shows choices	As the person types	After a press	Suggestions and results	No
Takes a value that is not listed	With allowCustomValue	No	Yes	Yes
Part of a form	Yes	Yes	No	Yes

1. With up to about five short options, show them all: radio buttons.
2. If the list is short enough to scan, and closed, it is a select.
3. If people would rather type than scroll, or the field takes a value that is not listed, it is a combobox field.
4. If typing leads to places to go rather than to a value, it is a search.
5. Several values are another component: a combobox holds one.
6. If the label stands elsewhere — a filter in a toolbar, a cell of a table — it is the bare combobox, named by its own label.

Do

link

• Write a label that names what is chosen, and keep it visible in a form.
• Use allowCustomValue only where a value that is not listed is a real answer.
• Give clearable to a combobox field whose value may be none, and name the button with clearLabel.
• When you load options, set status and statusText so the list says that it is waiting, how many it shows, or that it failed.
• Give emptyText, on the combobox field or once for the whole product with setWords({ emptyText }). Tanrei ships no words: without it a text that matches nothing draws no row, and the list has nothing to show.

Don’t

link

• Don’t use the placeholder as the label. It goes away as soon as the person types.
• Don’t save, navigate or submit on input. It fires at every keystroke; change is the committed value.
• Don’t treat a text that names no option as an error of the field. It is given up when the person leaves. If you want to say “choose one from the list”, set error and errorText yourself.
• Don’t put a combobox field inside a field. It is a field already; the control a field frames is the combobox.
• Don’t open the list on focus in a form of many fields: it covers the fields below at every stop.

Accessibility

link

Role

combobox

Labeling

The combobox field adds nothing to what its members expose and coordinates nothing: the Field gives the combobox its name, its description and its required, invalid and disabled states (FLD-8, FLD-10, FLD-11, FLD-14), and the combobox carries them on its own input, with its expanded state, its list and its active option (CMB-12, CMB-48). Assistive technology meets one editable combobox named by label, with a list of the same name, exactly as it meets a Field around a combobox written by hand.

Minimum target

The hit area meets the minimum target size even when the visual size is smaller. minimum 32px · pointer 44px · spacing 8px · touch 48px

Keyboard

Keys	Action
Every key	The combobox's (its accessibility block; CMB-16, CMB-20, CMB-21, CMB-26 to CMB-30). The combobox field handles no key and adds no focus stop (CBF-5).

Notes

• One level down is the same thing: a Field with a combobox in it, holding the same options. Every fixture has that pair as its twin, and the accessibility tree of the two is the same (CBF-1).
• The options are the product's, and they are the combobox's: the combobox field passes them on and does nothing with them (CBF-2). Value, text and open are the combobox's too, and the combobox field keeps no second copy that could disagree with it (CBF-3).
• On the web the two members stand in the combobox field's own shadow root, so the form meets the combobox field and not the combobox (CBF-4); focus passes through to the input (CBF-5); and the product's option elements stay its own children, read by the combobox through a slot.
• A list is not a second thing the component reports: choosing an option is setting its one value, so the combobox field is composed, not a feature.

Generated from specs/combobox-field.spec.json, tokens/sys/measure.tokens.json

What the component handles

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• The input is an editable combobox with a list box. Its name is label, drawn or hidden, and never the placeholder. The field gives it to the combobox, which carries it on its own input.
• The shown supporting or error text is its description, with optionalText while the field is optional.
• An error that appears while focus is in the field is announced once, politely.
• It is exposed as invalid while error is true, as required while required is set, as read-only, and as expanded while its list is open.
• Focus stays in the input while the list is open. The active option is its active descendant, so typing never stops editing the text. An option that typing made active is named once typing pauses for half a second, so that a screen reader reads the typed letter first and then the option Enter would choose; an option the arrow keys move to is named at once.
• The list is a list box named by the label. Each option has its name, its description, whether it is the chosen one, whether it is disabled, and its position among the options shown. A group is named by its title.
• A match is marked by weight, never by color alone. The label is read as one text.
• The status row is a live region: its text is read politely when it changes, and at once when the source failed. While loading, the list is marked busy and nothing is announced.
• While an input method is composing, the combobox handles no key.
• The chevron is a button for a pointer and for touch exploration, outside the focus order. The keyboard opens the list with Down Arrow.
• The clear button is a button named by clearLabel, and the next focus stop after the input.
• Escape closes the list and goes no further, so a dialog around the combobox stays open.
• The field’s hit area meets the minimum target, and options are at least the minimum target tall.
• At 200% text the label, the help, the options, the titles and the status row wrap. Only the text in the input stays on one line, and scrolls.
• In forced colors the field and the list gain an edge, the active option takes the highlight colors, and the chosen option is shown by its check.
• In a right-to-left layout the field and each row are mirrored, and each text keeps its own direction. The chevron, the clear button’s glyph and the check are not mirrored.

Known gaps on the web:

• The divider between two groups is not exposed as a separator: a list box holds options and groups only.
• The filter folds case, width and marks for every script alike. It does not match Hangul by its first consonant or kana by its reading.
• Before the element is defined, the options are text on the page without a control.

What you need to do

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• Give every combobox field a label, and every option a label and a value that is not empty.
• Give a clearable combobox field a clearLabel.
• Write statusText on the combobox field. Give emptyText, requiredText, optionalText and clearLabel on the combobox field, or once for the whole product with setWords(). Tanrei ships no words; a missing one is reported in development. See The product’s words.
• Validate the value yourself, set error, and write errorText so that it says how to put the answer right.
• Keep option values unique within a combobox field.