React · React Native · 16 components

Hard interactions, finished.

Animated Chorus is a set of motion components for the interactions that are hard to get right by hand: rolling numbers, streamed text, swaps that resize, sheets, pagers, swipe actions and lists that animate only what changed. One tag and your data. No provider, no setup.

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Install

npm install @kkwaenggwari/animated-chorus

Measured on this build

Chrome, 2026-09-28. Every condition and sample is in the performance guide. How it was measured

28.0KBKB gzip for all 16 exports
The whole web entry, minified. React is the only peer.
0JS frame callbacks while animating
A number, a height and a highlight changing together: the browser plays all 12 animations.
1React commit per value change
MotionNumber renders when the value changes, never while it rolls.
11React commits for 3000 streamed characters
MotionStream appends characters directly and folds them into React a few times per second.

01Easiest

One tag and your data

Every component works on its own: no provider, wrapper component or setup call. Collections take items and renderItem, and your layout, text and styles stay yours.

Import one component and pass a value. That is the whole integration.
Lists, tabs and pagers read your array; keys default to item.id.
Text stays real text: it wraps, scales with the font and can be selected.

```
<MotionNumber value={total} />;
```

<MotionSwap value={status}>{label}</MotionSwap>;

<MotionHeight open={open}>{details}</MotionHeight>;

<MotionHighlight items={tabs} value={tab} onValueChange={setTab} />;

<MotionList items={tasks} renderItem={(task) => task.title} />;

```
<ProgressRing value={progress} />;
```

Six live components, and the one line of code behind each.

Preparing the example…

JavaScript is off. The code below is the complete example.

App.jsx

import { useState } from 'react';
import {
  MotionHighlight,
  MotionNumber,
  MotionSwap,
  motionTokens,
} from '@kkwaenggwari/animated-chorus';
import './styles.css';

const plans = [
  { id: 'starter', label: 'Starter', price: 0, points: ['1 project', 'Community support'] },
  {
    id: 'team',
    label: 'Team',
    price: 24,
    points: ['10 projects', 'Shared workspaces', 'Priority support'],
  },
  {
    id: 'scale',
    label: 'Scale',
    price: 196,
    points: ['Unlimited projects', 'Single sign-on', 'Audit log', 'Dedicated support'],
  },
];

export default function App({ hover = true, effect = 'up', spring = 'default' }) {
  const [plan, setPlan] = useState('team');
  const current = plans.find((item) => item.id === plan);
  // "default" is not a preset: undefined keeps the component's own motion.
  const transition = motionTokens.spring[spring];

  return (
    <div className="card">
      <MotionHighlight
        items={plans}
        value={plan}
        onValueChange={setPlan}
        hover={hover}
        transition={transition}
        className="tabs"
        itemClassName="tab"
        highlightClassName="tab-highlight"
        renderItem={(item, { selected }) => (
          <span className={selected ? 'tab-label on' : 'tab-label'}>{item.label}</span>
        )}
      />
      <p className="price">
        <MotionNumber value={current.price} prefix="$" transition={transition} />
        <span className="per">per month</span>
      </p>
      <MotionSwap as="div" inline={false} value={plan} effect={effect} transition={transition}>
        <ul className="points">
          {current.points.map((point) => (
            <li key={point}>{point}</li>
          ))}
        </ul>
      </MotionSwap>
    </div>
  );
}

styles.css

.card {
  display: grid;
  gap: 18px;
  max-width: 420px;
  margin: 24px auto;
  padding: 22px;
  border: 1px solid #cfe8dc;
  border-radius: 18px;
  background: #fff;
}

.tabs {
  display: flex;
  gap: 2px;
  padding: 4px;
  border-radius: 999px;
  background: #eaf6f0;
}

.tab {
  flex: 1;
  min-height: 40px;
  border: 0;
  border-radius: 999px;
  background: none;
  font:
    650 15px system-ui,
    sans-serif;
  color: #0e2e24;
  cursor: pointer;
}

.tab-highlight {
  border-radius: 999px;
  background: #fff;
  box-shadow: 0 0 0 1px #cfe8dc;
}

.tab-label {
  color: #5b616b;
  transition: color 0.2s;
}

.tab-label.on {
  color: #176b52;
}

.price {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin: 0;
  font:
    800 44px/1 system-ui,
    sans-serif;
  font-variant-numeric: tabular-nums;
  color: #0e2e24;
}

.price .per {
  font-size: 15px;
  font-weight: 500;
  color: #5b616b;
}

.points {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.points li {
  padding: 12px 14px;
  border-radius: 12px;
  background: #f4faf7;
  color: #16181d;
}

02Fastest

The browser plays it. React stays still.

On the web there is no animation library to load: components hand their motion to the Web Animations API, so a rolling number or a resizing panel costs no JavaScript per frame and no React render while it moves.

0 JS frame callbacks while 12 animations run together.
One React commit per value change, not one per frame.
Streamed text: 11 React commits for 3000 characters. The example below counts its own renders.

Preparing the example…

JavaScript is off. The code below is the complete example.

App.jsx

import { useEffect, useRef, useState } from 'react';
import { MotionStream } from '@kkwaenggwari/animated-chorus';
import './styles.css';

const answer =
  'Motion helps people follow change. When a total updates, a rolling number shows which way it moved. ' +
  'When a panel opens, the height that follows its content keeps the reader in place. ' +
  'When an answer arrives in bursts, a steady reveal turns the bursts into reading: nothing waits for the ' +
  'next packet, and nothing is dumped at once. The pace speeds up only when a backlog builds, so the text ' +
  'never falls far behind what the server has already sent.';

// Network-like bursts: long pauses, then a lot of text at once.
const pauses = [300, 1100, 250, 1500, 400, 900];

export default function App({ speed = 90, catchUp = 900, chunk = 160, effect = 'fade' }) {
  const [received, setReceived] = useState(0);
  const [chunks, setChunks] = useState(0);
  const renders = useRef(0);
  renders.current += 1;

  useEffect(() => {
    if (received >= answer.length) return;
    const timer = setTimeout(
      () => {
        setReceived((current) => Math.min(answer.length, current + chunk));
        setChunks((count) => count + 1);
      },
      pauses[chunks % pauses.length],
    );
    return () => clearTimeout(timer);
  }, [received, chunks, chunk]);

  const askAgain = () => {
    setReceived(0);
    setChunks(0);
  };

  return (
    <div className="chat">
      <p className="question">Why does motion help an interface?</p>
      <p className="answer">
        <MotionStream
          text={answer.slice(0, received)}
          speed={speed}
          catchUp={catchUp}
          effect={effect}
        />
      </p>
      <footer>
        <output>
          {chunks} chunks · App rendered {renders.current} times
        </output>
        <button onClick={askAgain}>Ask again</button>
      </footer>
    </div>
  );
}

styles.css

.chat {
  display: grid;
  gap: 16px;
  max-width: 620px;
  margin: 0 auto;
  padding: 24px 20px;
}

.question {
  justify-self: end;
  max-width: 80%;
  margin: 0;
  padding: 10px 16px;
  border-radius: 18px 18px 4px 18px;
  background: #176b52;
  color: #fff;
}

.answer {
  min-height: 180px;
  margin: 0;
  padding: 16px 18px;
  border: 1px solid #cfe8dc;
  border-radius: 18px 18px 18px 4px;
  background: #fff;
  color: #16181d;
  line-height: 1.65;
}

footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

output {
  font:
    600 13px ui-monospace,
    Consolas,
    monospace;
  color: #176b52;
}

footer button {
  min-height: 40px;
  padding: 0 16px;
  border: 1px solid #cfe8dc;
  border-radius: 999px;
  background: #fff;
  font:
    600 14px system-ui,
    sans-serif;
  cursor: pointer;
}

03Most stable

Interrupt anything. It never jumps.

Every new value starts from what is on screen and springs keep their speed, so rapid clicks, bursts of data and reversals look intentional. When the motion ends, nothing is left running.

Numbers never split: remaining places slide while they roll.
200 new values 5 ms apart: 0 animations left afterwards and the exact final text.
Safe under React StrictMode. In a background React Native app, motion settles to its end state.

Preparing the example…

JavaScript is off. The code below is the complete example.

App.jsx

import { useEffect, useState } from 'react';
import { MotionNumber, motionTokens } from '@kkwaenggwari/animated-chorus';
import './styles.css';

const burst = [12, 37, 85, 140, 9, 260, 48, 530, 21, 1100, 75, 2300];

export default function App({ mode = 'roll', direction = 'auto', spring = 'default' }) {
  const [value, setValue] = useState(1280);
  const [changes, setChanges] = useState(0);
  const [bursting, setBursting] = useState(false);

  const change = (next) => {
    setValue(next);
    setChanges((count) => count + 1);
  };

  // Twelve rising values, 90 ms apart, like a live counter: each arrives mid-motion.
  useEffect(() => {
    if (!bursting) return;
    let step = 0;
    const timer = setInterval(() => {
      const delta = burst[step];
      setValue((current) => Math.max(0, current + delta));
      setChanges((count) => count + 1);
      step += 1;
      if (step === burst.length) {
        clearInterval(timer);
        setBursting(false);
      }
    }, 90);
    return () => clearInterval(timer);
  }, [bursting]);

  return (
    <div className="counter">
      <MotionNumber
        className="value"
        value={value}
        intl
        locale="en-US"
        mode={mode}
        direction={direction}
        transition={motionTokens.spring[spring]}
      />
      <p className="changes">{changes} changes, no jumps</p>
      <div className="buttons">
        <button onClick={() => change(Math.max(0, value - 100))}>−100</button>
        <button onClick={() => change(value + 1)}>+1</button>
        <button onClick={() => change(value + 250)}>+250</button>
        <button onClick={() => change(value * 10)}>×10</button>
        <button onClick={() => change(Math.round(value / 10))}>÷10</button>
        <button className="burst" onClick={() => setBursting(true)} disabled={bursting}>
          Burst ×12
        </button>
      </div>
    </div>
  );
}

styles.css

.counter {
  display: grid;
  justify-items: center;
  gap: 14px;
  padding: 36px 20px 28px;
}

.value {
  font:
    800 clamp(48px, 12vw, 88px)/1.05 system-ui,
    sans-serif;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.03em;
  color: #0e2e24;
}

.changes {
  margin: 0;
  color: #5b616b;
  font-size: 14px;
}

.buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
}

.buttons button {
  min-width: 64px;
  min-height: 44px;
  padding: 0 16px;
  border: 1px solid #cfe8dc;
  border-radius: 999px;
  background: #fff;
  font:
    650 15px system-ui,
    sans-serif;
  color: #0e2e24;
  cursor: pointer;
}

.buttons button:hover {
  border-color: #176b52;
}

.buttons .burst {
  border-color: #176b52;
  background: #176b52;
  color: #fff;
}

.buttons .burst:disabled {
  opacity: 0.5;
}

16 components, grouped by the job they do

Numbers and text, content that changes size, selection, lists, gestures, overlays and progress. Each one has a live workbench with its props on the side.

All components

Put together

Complete screens that combine several components, each with its settings outside the example.

All examples

The same import on the web and React Native

Metro selects the native implementation and web bundlers select the DOM one. Each platform plays motion the way it plays best.

App.jsx

// Web and React Native: the same import.
import { MotionNumber, MotionList } from '@kkwaenggwari/animated-chorus';

export function Score({ points, players }) {
  return (
    <>
      <MotionNumber value={points} />
      <MotionList items={players} renderItem={(player) => player.name} />
    </>
  );
}

Part	Web	React Native
Transforms and opacity	Web Animations API, springs sampled analytically	`Animated` with the native driver
Width and height	Web Animations API	`Animated` with the JS driver, because it is layout
Streamed text	Characters appended and faded in; a few React renders per second	A real `Text`, revealed without a fade
Sheets and zoom	A native `dialog` in the top layer	A transparent `Modal`; the back button closes it

Start in two minutes

Install, import one component, pass a value.

npm install @kkwaenggwari/animated-chorus

Hard interactions, finished.

Measured on this build

One tag and your data

The browser plays it. React stays still.

Interrupt anything. It never jumps.

16 components, grouped by the job they do

Numbers and text

Content and size

Selection and paging

Lists

Gestures

Overlays

Progress

Put together

The same import on the web and React Native

Start in two minutes

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