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@jsvision/ui / ComboBox

Class: ComboBox<T> ​

Documented in: Combo box

Defined in: ui/src/dropdown/combo-box.ts:104

A dropdown selector: a text field + a trailing ▐↓▌ button opening a ListView<T> popup. Editable (free text + filter) or select-only (read-only picker + type-ahead). See the module docs.

Example ​

ts
import { ComboBox, Group, createEventLoop, signal } from '@jsvision/ui';
import { resolveCapabilities } from '@jsvision/core';

const caps = resolveCapabilities({ env: {}, platform: 'linux' }).profile;
const items = signal(['TypeScript', 'JavaScript', 'Python', 'Rust', 'Go']);
const value = signal<string | null>(null);
const combo = new ComboBox<string>({ items, getText: (s) => s, value, editable: true });
combo.layout = { position: 'absolute', rect: { x: 1, y: 1, width: 22, height: 1 } };

const controls = new Group();
controls.add(combo);
const loop = createEventLoop({ width: 40, height: 12 }, { caps });
loop.mount(controls);
loop.focusView(combo.input); // the field is the focus target
// Typing filters the candidates; Alt+↓ opens the list; Enter picks (sets value + text).

Extends ​

Type Parameters ​

T ​

T

Constructors ​

Constructor ​

new ComboBox<T>(opts): ComboBox<T>

Defined in: ui/src/dropdown/combo-box.ts:128

Parameters ​

opts ​

ComboBoxOptions<T>

The items + getText + two-way value (and optional text), the editable flag, an optional filter/onSelect/command/maxRows.

Returns ​

ComboBox<T>

Overrides ​

Group.constructor

Properties ​

background? ​

optional background?: keyof Theme

Defined in: ui/src/view/group.ts:64

Optional background theme role filled before children compose, so overlap never leaks cells.

Inherited from ​

Group.background

bounds ​

bounds: Rect

Defined in: ui/src/view/view.ts:65

Parent-relative integer rect; written by the layout pass — read it in draw/hit-testing.

Inherited from ​

Group.bounds

button ​

protected readonly button: ComboButton

Defined in: ui/src/dropdown/combo-box.ts:122

castsShadow ​

castsShadow: boolean = false

Defined in: ui/src/view/view.ts:78

When true, the renderer paints a drop shadow on the cells just below and to the right of this view, in paint order (a later sibling's shadow falls over an earlier one). Default false. The Desktop sets it per window.

Inherited from ​

Group.castsShadow

centered ​

centered: boolean = false

Defined in: ui/src/view/view.ts:86

When true, the layout pass recentres this view within its parent after layout — origin = (parent - self) / 2 on both axes. Intended for absolutely-placed views (a modal dialog, a message box) whose size is fixed and whose origin would otherwise be placed by the caller. Default false; Dialog sets it when centered.

Inherited from ​

Group.centered

children ​

readonly children: View[] = []

Defined in: ui/src/view/group.ts:62

Ordered children; array order is paint order (back-to-front).

Inherited from ​

Group.children

command? ​

protected readonly optional command?: string

Defined in: ui/src/dropdown/combo-box.ts:120

editable ​

protected readonly editable: boolean

Defined in: ui/src/dropdown/combo-box.ts:117

filtered ​

readonly filtered: () => T[]

Defined in: ui/src/dropdown/combo-box.ts:114

The current candidate list — items in select-only mode, filtered by text when editable.

Returns ​

T[]

filterFn ​

protected readonly filterFn: (item, text) => boolean

Defined in: ui/src/dropdown/combo-box.ts:118

Parameters ​

item ​

T

text ​

string

Returns ​

boolean

focusable ​

focusable: boolean = false

Defined in: ui/src/view/view.ts:94

Whether this view can receive keyboard focus. Effective focusability also requires the view to be visible and enabled with no hidden/disabled ancestor. Default false; the focus manager drives the state.focused flag.

Inherited from ​

Group.focusable

getText ​

protected readonly getText: (item) => string

Defined in: ui/src/dropdown/combo-box.ts:116

Parameters ​

item ​

T

Returns ​

string

input ​

readonly input: Input

Defined in: ui/src/dropdown/combo-box.ts:112

The composed text field (the focus target; exposed for focusing + testing).

items ​

readonly items: Signal<T[]>

Defined in: ui/src/dropdown/combo-box.ts:106

The source items.

layout ​

layout: LayoutProps = {}

Defined in: ui/src/view/view.ts:69

Layout props for this view (direction, size, padding, absolute placement, …).

Inherited from ​

Group.layout

maxRows ​

protected readonly maxRows: number

Defined in: ui/src/dropdown/combo-box.ts:121

onSelect? ​

protected readonly optional onSelect?: (index, item) => void

Defined in: ui/src/dropdown/combo-box.ts:119

Parameters ​

index ​

number

item ​

T

Returns ​

void

postProcess ​

postProcess: boolean = false

Defined in: ui/src/view/view.ts:98

Take part in the post-process sweep (after the focused view sees the event).

Inherited from ​

Group.postProcess

preProcess ​

preProcess: boolean = false

Defined in: ui/src/view/view.ts:96

Take part in the pre-process sweep (root→down, before the focused view sees the event).

Inherited from ​

Group.preProcess

state ​

readonly state: ViewState

Defined in: ui/src/view/view.ts:67

Draw-against flags. The object reference is fixed; individual fields mutate (e.g. focused).

Inherited from ​

Group.state

text ​

readonly text: Signal<string>

Defined in: ui/src/dropdown/combo-box.ts:110

The field text.

value ​

readonly value: Signal<T | null>

Defined in: ui/src/dropdown/combo-box.ts:108

The selected value (null = none / no exact match in editable mode).

Methods ​

accelerators() ​

accelerators(): readonly string[]

Defined in: ui/src/view/view.ts:114

The Alt+hotkey accelerator characters (lowercase) this view claims in its focus scope, for duplicate-accelerator detection. The base returns none; accelerator-bearing widgets (Button/Label/CheckGroup/RadioGroup) override it to report their ~X~ hotkey(s).

Returns ​

readonly string[]

The claimed accelerator chars, or an empty list when the view claims none.

Inherited from ​

Group.accelerators

add() ​

add(child): void

Defined in: ui/src/view/group.ts:88

Add a child, appending it on top (later in the array draws in front). If this group is already mounted, the child mounts immediately — its scope nested under this group's — and a reflow is scheduled for the new layout; otherwise the child mounts when this group itself mounts.

Parameters ​

child ​

View

The view to append.

Returns ​

void

Inherited from ​

Group.add

addDynamic() ​

addDynamic(build): void

Defined in: ui/src/view/group.ts:135

Add children reactively from a Show/For accessor, so the set of children updates itself as signals change. When the group is mounted, an effect reads the accessor, mounts any newly produced views, unmounts any that disappeared (firing their onCleanup), and schedules a reflow on change. Pass a factory that builds the combinator inside itself, not an already-built accessor — this lets the group own and dispose the combinator's reactive nodes on unmount.

Parameters ​

build ​

DynamicBuilder

A factory that constructs the combinator, e.g. () => Show(cond, then) or () => For(each, key, render).

Returns ​

void

Example ​

ts
import { Group, signal, Show } from '@jsvision/ui';

const open = signal(false);
const group = new Group();
group.addDynamic(() => Show(() => open(), () => new Panel())); // Panel appears when `open` is true

Inherited from ​

Group.addDynamic

bind() ​

bind<T>(reader, apply?, opts?): void

Defined in: ui/src/view/view.ts:228

Bind a reactive value to a redraw. Creates an effect (owned by this view's scope) that reads reader() — subscribing to whatever signals it touches — runs the optional apply(value), then requests a frame: a repaint by default, or a reflow when { relayout: true }. It re-runs automatically whenever those signals change, and is disposed when the view unmounts.

Call it from onMount, not the constructor — the view's scope only exists once mounted, so a pre-mount bind throws rather than silently dropping the binding.

Type Parameters ​

T ​

T

Parameters ​

reader ​

() => T

Reads the reactive source; the signals it reads become dependencies.

apply? ​

(v) => void

Optional: apply the read value to the widget (e.g. store it in a field).

opts? ​

Pass { relayout: true } when the change affects layout, so it reflows instead of just repainting.

relayout? ​

boolean

Returns ​

void

Example ​

ts
import { signal } from '@jsvision/ui';

const count = signal(0);
// `status` is a View whose draw() reads count():
status.onMount(() => {
  status.bind(() => count()); // repaint the status line whenever `count` changes
});

Inherited from ​

Group.bind

bindValueText() ​

protected bindValueText(): void

Defined in: ui/src/dropdown/combo-box.ts:162

Wire the mode-specific one-way binding between value and text. Editable: value tracks the exact getText-match of text among items (else null). Select-only: text mirrors getText(value). Each direction reads only the OTHER signal, so there is no feedback loop.

Returns ​

void

derived() ​

protected derived<T>(fn): () => T

Defined in: ui/src/view/view.ts:261

Create a stable derived accessor owned by this view's scope. The returned () => T keeps the same identity for the life of the view, so it is safe to build in the constructor and hand to child views before this view mounts. The backing computed is created lazily under the view's own scope, so it is always owned and disposed at unmount — unlike a bare computed() in the constructor, which would run before any scope exists, leak, and warn.

Reads behave sensibly across the lifecycle:

  • Before mount: evaluates fn() directly (correct current value, nothing persisted). Good for a pre-mount natural-size measure.
  • After mount: builds and memoizes a computed(fn) under the view's scope.
  • After an unmount→remount: the memo is keyed to the scope it was built under, so a remounted view (which gets a fresh scope) re-derives under the new scope instead of returning the previous mount's disposed, now-frozen computed — keeping a Show/For-remounted widget reactive.

Type Parameters ​

T ​

T

Parameters ​

fn ​

() => T

The derivation (pure; the signals it reads become the computed's dependencies).

Returns ​

A stable accessor; call it to read the derived value.

() => T

Inherited from ​

Group.derived

desiredCaret() ​

desiredCaret(): Point | null

Defined in: ui/src/view/view.ts:192

Where this view wants the hardware text cursor, in view-local cells, or null for no cursor (the default — most views never show one). A focused text input overrides this to place the caret at the edit position; the event loop reads it after each frame, converts it to an absolute cell, and moves the terminal cursor there.

Returns ​

Point | null

The view-local caret point (0-based, relative to this view's origin), or null.

Inherited from ​

Group.desiredCaret

draw() ​

draw(ctx): void

Defined in: ui/src/view/group.ts:75

Fill the background role (if set) across the group rect; children are composed by the render root.

Parameters ​

ctx ​

DrawContext

Returns ​

void

Inherited from ​

Group.draw

focusSignal() ​

focusSignal(): Signal<void>

Defined in: ui/src/view/view.ts:136

Subscribe to this view's focus changes. Reading the returned signal inside a bind/effect re-runs that effect whenever this view gains or loses focus — including from another view (e.g. a Label repainting when the control it labels is focused). The signal notifies on every poke even without a value change. Lazy: the backing signal is created on first call.

Returns ​

Signal<void>

A signal that ticks whenever this view gains or loses focus.

Example ​

ts
// Inside a widget's onMount, repaint whenever `other` view's focus changes:
this.onMount(() => this.bind(() => other.focusSignal()()));

Inherited from ​

Group.focusSignal

invalidate() ​

invalidate(): void

Defined in: ui/src/view/view.ts:197

Request a repaint of this view. A no-op before the view is mounted (the first frame paints everything).

Returns ​

void

Inherited from ​

Group.invalidate

invalidateLayout() ​

invalidateLayout(): void

Defined in: ui/src/view/view.ts:202

Request a reflow (re-run layout, then repaint). Use this when a change affects size/position, not just pixels.

Returns ​

void

Inherited from ​

Group.invalidateLayout

measure()? ​

optional measure(available): Size2D

Defined in: ui/src/view/view.ts:71

Optional intrinsic-size hook for auto sizing — return the size this view wants for available.

Parameters ​

available ​

Size2D

Returns ​

Size2D

Inherited from ​

Group.measure

onCleanup() ​

onCleanup(fn): void

Defined in: ui/src/view/view.ts:298

Register a teardown callback that runs once when this view unmounts. Requires a mounted view — so call it from within onMount. Use it to release anything the view acquired (a timer, an external subscription).

Parameters ​

fn ​

() => void

The teardown callback.

Returns ​

void

Inherited from ​

Group.onCleanup

onEvent() ​

onEvent(ev): void

Defined in: ui/src/dropdown/combo-box.ts:185

Open on Down / Alt+Down while the field is focused (the ComboBox sees the key because the focused field is its descendant). A mouse-down on the trailing button opens via ComboButton.

Parameters ​

ev ​

DispatchEvent

The dispatch envelope.

Returns ​

void

Overrides ​

Group.onEvent

onMount() ​

onMount(fn): void

Defined in: ui/src/view/view.ts:283

Register a callback to run once when the view becomes live (after its first layout gives it bounds). This is where to call bind, since the view's reactive scope exists by then. Registering after the view is already live runs the callback immediately.

Parameters ​

fn ​

() => void

Post-mount setup.

Returns ​

void

Inherited from ​

Group.onMount

open() ​

protected open(ev): void

Defined in: ui/src/dropdown/combo-box.ts:199

Focus the field, then open the anchored popup over the current candidates. Select-only lists get typeAhead; editable lists show the filtered snapshot at open time. A no-op with no overlay host.

Parameters ​

ev ​

DispatchEvent

The dispatch envelope (source of the popup host + focus seam).

Returns ​

void

pick() ​

protected pick(item): void

Defined in: ui/src/dropdown/combo-box.ts:249

Commit a picked item. Editable sets text = getText(item) (⇒ value via the bind); select-only sets value = item (⇒ text via the bind). Out-of-range index (undefined) is a no-op.

Parameters ​

item ​

T | undefined

The picked item, or undefined when the display index is out of range.

Returns ​

void

remove() ​

remove(child): void

Defined in: ui/src/view/group.ts:104

Remove a child: dispose its scope (recursively disposing its descendants and running their onCleanup), detach it, and schedule a reflow. Removing a non-child (or removing twice) is a safe no-op.

Parameters ​

child ​

View

The view to remove.

Returns ​

void

Inherited from ​

Group.remove

selectByClick()? ​

optional selectByClick(): void

Defined in: ui/src/view/view.ts:182

Optional "select + raise on click" hook. Left undefined on the base, so a plain view is not a select/raise target. A container that owns z-order (a Window) overrides it to select and raise itself. The hit-test invokes the first ancestor that defines this — before delivering the mouse-down — so a click always raises the window even if the interior also consumes the click.

Returns ​

void

Inherited from ​

Group.selectByClick