SplitFlap

A readout that turns over like a departures board: each character flips through the ones between where it is and where it's going, flap by flap — fast when it's far, slowest on the last one — and each flap ticks. The flaps are the neutral cap's plastic in a recessed well.

Feel A mechanism you can hear: every flap between here and there.

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Or let the agent fetch it: get_component("split-flap") on the Echo MCP server.

Installation

npx echo-ui-cli add split-flap

First time? Run npx echo-ui-cli init once — it sets the project up, and add refuses to run before it.

At a glance

Version: 0.3.0
Weight: 1.2 KB · 1.6 KB with what it imports · 819 B of CSS (minified and gzipped; React not counted)
Needs: roll (Echo, brought with it)
Reduced motion: It jumps to the value.
Sound: A short tick per flap, inside a SoundProvider.

Usage

tsx

import { SplitFlap } from "@/echo/split-flap";

<SplitFlap value={count} length={4} />

Composition

SplitFlap → a well of flaps, each two halves and two turning leaves

Examples

A count

Pads to four digits.

tsx

<SplitFlap value={visitors} length={4} label="Visitors" live />

Words

Letters turn through the alphabet.

tsx

<SplitFlap value="BOARDING" length={8} />

Accessibility

The flaps are one image named by the value (and label), so it's read once, not letter by letter.
live announces changes politely, from outside the image where it can be heard.

Tested against WCAG 2.2 AA on every release:

axe — No axe violations, in the component's own gallery and on its page.
keyboard — Every action is reachable and operable from the keyboard alone.
focus-visible — Focus is visible on every focusable part, in normal and forced-colors mode.
forced-colors — State stays visible when the look's colours are replaced by the system's.
target-size — Every target's real hit area is at least 24×24px, at every density.
reflow — Content reflows into 320px and survives a doubled text size.

Not covered: screen-reader: not yet verified by a person. Everything above is a machine check; a person has not yet driven this component with a screen reader.

Motion & sound

Reduced motion: It jumps to the value.
Sound: A short tick per flap, inside a SoundProvider.

Props

SplitFlap props
Prop	Type	Default
`value` requiredWhat it shows. Numbers pad with zeros to `length`; text with spaces.	`number \| string`
`length`How many flaps. Defaults to the value's own length.	`number`
`label`What the value is, for its name: "Visitors" reads "Visitors 1024".	`string`
`live`Announce changes politely.	`boolean`
`size`How big each flap is: sm 44px tall, md (the default) 64px, lg 84px.	`"sm" \| "md" \| "lg"`

Anti-patterns

Never use it for a value that changes many times a second: it can't keep up, by design.
Never use it for the only copy of important text: it's slow to read on purpose.

Changelog

v0.3.0 · 2026-10-12 · AddedThe drawn device (echo-ui-core, echo-ui-cli, every component that draws its own material). A seed's new render setting is molded (Echo as it has always been: plastic lit by one key light) or drawn: the same parts drawn in the ink, the way a spec sheet draws a key. Every part is outlined at one weight (--echo-line, --echo-line-width), hollow on the body; a raised part stands on a hard ink edge as deep as it rises and travels down it when pressed; a recess is an outline drawn inside; something floating stands on a deeper edge. There's no light, so no gloss, no soft shadow and no glow: what a molded device lights (an LED, the rail, a readout, the focus ring, a fader's knob, a radio's pip) is solid ink, and a low-emphasis action is its label underlined. In black and white (the accent the ink) "on" is solid ink and what's drawn on it inverts: a switch's thumb turns paper, a fader's knob is knocked out with a paper ring. The primary key is the paper key that stands highest, on an ink edge twice as deep as a neutral one's, the way a spec sheet draws its CTA. The accent stays the seed's own colour as a flat fill for what's on (a chosen segment, a checked box, a slider's travel, a switch that's on), so an acid highlighter is acid, not the olive a molded device holds it to; what's drawn on it is the ink, or the body when the accent is too deep for the ink. Pressing, travel, sound, what each material is for and every contrast guarantee are unchanged. npx echo-ui-cli style set render drawn turns it on; a style sets it in its seed; the published style and config schemas describe it, and DESIGN.md says how a drawn device builds. A molded device renders exactly as before: every line is 0px wide there, and each drawn value a component reads (--echo-drawn-fill, -on-fill, -ink, -rule, -glass, -hollow, -decoration) is initial, so it falls back to what the component always drew. HardwareButton's bed is the one new hand-tuned shadow: a drawn key stands on its own edge instead of being drawn in a recess.
v0.3.0 · 2026-10-12 · ChangedEvery item needs echo-ui-core 0.3.0 (all components). The drawn device, readability past AA and the design tests live in core, and the components that use them are built against it, so each item now declares echo-ui-core >=0.3.0 <0.4.0. Update core with the items: npm install echo-ui-core@^0.3.0 (or your package manager's), then npx echo-ui-cli update. An item whose files didn't change is the same code under a new version; the 0.2.0 files stay published.
v0.2.0 · 2026-10-04 · AddedThe light device (echo-ui-core, echo-ui-cli). Echo can be light: a pale chassis makes a device molded in light plastic, like a white calculator or a cream radio, and a dark one makes the device Echo has always been. There's no setting and no mode to switch; the chassis decides (devicePolarity, and values.polarity on the theme). On a light device the page is light: its ground, the well, is the body barely set in. Caps get their own ladder, a step lighter than the body with a lit rim that stops short of white, so they keep their bevel; undersides and seams are shaded darker; dim text moves toward the ground by the same step as on a dark device, and reads about 6:1 on it. Screens are paper glass printed in ink, because a glow on a pale body is a smudge. What's lit (an LED, the current rail) is still the accent, held to 3:1 on every ground, so on is brighter than off; the text it prints (a readout, a count, a current tab) and the focus ring are the accent's ink, a step deeper and held to AA, in the new accent-ink role. The primary cap is the same cap as a dark device's, the accent with a light label: its label is the new primary-cap-ink role, and progress cells, loader dots and a meter's fill, the same plastic, read 3:1 on the page. A neutral cap or a slider that fills with it under its own dark label fills with the new pour-* roles, the accent's pale stops. Shadows are drawn at half their weight, in a deep colour of the body's own hue (--echo-cast-ink) instead of black. Every guarantee holds as it does on a dark device, and the contrast sweep now runs on light bodies too. A dark seed makes exactly the theme it did before, and the new roles equal the ones they stand for there. The components that mixed a recess toward black, painted paper in the text colour or lit a pillow of light with it read the theme's new --echo-shade-ink, --echo-paper-stock and --echo-paper-ink instead, with the old value as the fallback, and a reflective screen reads --echo-screen-*; the components that print a lit label read --echo-primary-cap-ink and --echo-accent-ink the same way; every rail is drawn in the glow, and every focus ring, the ring recipes included, in the ink. style use wears a light style now, and style check says which device a style makes. A dark screen tint on a light body is still refused: one text colour can't serve both, and the theme says so.
v0.2.0 · 2026-10-04 · AddedDigits that roll: roll on LcdChip, StatTile and NumberField, and the useRoll hook under them. Pass roll and a new value steps each digit through the ones in between, all together, fast when it's far and slowest on the last step: 18 → 21 shows 29, 20, 21. A falling number rolls back, 99 → 100 turns the nines over and puts a 1 in front, and anything that isn't a digit (a comma, a colon) swaps at once. The digits in between are drawn but hidden from assistive technology, so the value is still read once, as it is; under reduced motion it doesn't roll. On NumberField it replaces the slide a step used to give the whole number, and typing never rolls. It's off by default, so nothing changes until you pass it. SplitFlap now turns on the same drum (echo-roll, which each of these installs with it); it looks and sounds the same.
v0.2.0 · 2026-10-04 · AddedSix other kinds of physics. PullCord is a switch you pull: the cord stretches, clicks at a detent and changes as you let go. SplitFlap is a readout that turns over flap by flap. LightSource makes your pointer the light the HardwareButtons inside it are lit by. Magnetic makes the buttons inside lean toward your hand before you touch them. ThrowStack is a stack of Panels you flick away with the speed you gave them. Ripple is a surface that sends a wave from where you press. All of them are built from Echo's own caps, panels and roles, have a keyboard path, and hold still under reduced motion.
v0.2.0 · 2026-10-04 · ChangedComponents whose shadow is a recipe read it by name. 71 shadows in 54 items now say var(--echo-shadow-<name>, <the same shadow>), so they look exactly as they did (every docs page was compared before and after) and follow a theme's recipes. Scope declares the recipes that read the accent again, so a Scope's own colour still reaches its focus rings and glows, and reflective screens do the same for theirs. Shadows that move with their part (a cap's drop as it's pressed) stay in the component.
v0.2.0 · 2026-10-04 · ChangedComments only, no behaviour change. Comments in the component source used to cite documents, milestones and ticket numbers from Echo's own planning, none of which exist in your project. The citations are gone and the sentences around them stay. Where a comment was only a citation, it now says what it meant. Three development warnings (HardwareButton's engraved/caption checks and StatusDot's missing-label check) also dropped the ticket code at the end of the message. echo-ui diff will show changes in most items; none of them are to code.
v0.2.0 · 2026-10-04 · ChangedAn item's version is now a function of declared data, not of how the changelog is formatted. The version an item ships under is published once and never rewritten, and it used to be inferred from prose: a regex for a bolded "Breaking" run across the whole unreleased section, and attribution by "does a bullet mention this name in backticks". One breaking entry therefore moved every item that changed that cycle, and an entry explaining that "Menu and Sheet are unchanged here" filed itself as a change to Menu and Sheet — which it really had.
v0.2.0 · 2026-10-04 · ChangedThe agent brief says Echo has not shipped. llms.txt and the MCP server's instructions led with npx echo-ui-cli init, and that name on npm is a reserved stub with no executable — so a model following the brief wrote an install step that fails with npx's own error. The brief now opens with the caveat, and the docs carry it on every surface that shows a command. One switch (CLI_RELEASED) silences all of them at launch, and a test refuses to let one move without the others. Affects all components only in what the brief says about installing them; no item's props, CSS or rendered semantics change.
v0.2.0 · 2026-10-04 · ChangedEcho's home is echo-ui.com. The registry, the docs and the packages all move to it from echo.nawwara.studio. Nothing was published under the old host, so no echo.json anywhere points at it and there is nothing to migrate — this is the last release where that is true.
v0.2.0 · 2026-10-04 · ChangedWeights, line heights, letter-spacing, z-index, border widths and icon sizes come from the theme scales in all components, with the old value as a fallback, so components keep working with echo-ui-core@0.0.1. Strays moved to the nearest step: most by under a pixel; HardwareButton icons are 14/16/20px (were 15/17/19).
v0.2.0 · 2026-10-04 · FixedContent now reflows into a 320px screen (400% zoom) and survives a doubled browser text size (WCAG 1.4.10, 1.4.4), across all components. Select's 180px floor, NumberField's readout, Segmented and Steps as flex items, EmptyState's grid columns, and Avatar's fixed-pixel disc all gave way; Panel counts its padding inside a width you set (box-sizing: border-box), so a <Panel style={{ width: 220 }}> is now 220px wide overall rather than 260px.

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