09Live regions that split the reading order

<main class="stage">
  <div class="lr is-demo">
    <div class="lr__grid">
      <div class="lr__col is-live" data-lane="polite">
        <span class="lr__tag"><code>role="status"</code> waits its turn</span>
        <p class="lr__card" role="status" aria-live="polite" aria-atomic="true" aria-label="Polite notification lane">
          <span class="lr__dot" aria-hidden="true"></span>
          <span class="lr__msg">Mail sent</span>
        </p>
      </div>
      <div class="lr__col" data-lane="alert">
        <span class="lr__tag"><code>role="alert"</code> cuts in</span>
        <p class="lr__card" role="alert" aria-live="assertive" aria-atomic="true" aria-label="Urgent notification lane">
          <span class="lr__dot" aria-hidden="true"></span>
          <span class="lr__msg">The payment was declined</span>
        </p>
      </div>
    </div>
    <div class="lr__say" id="lr-say" data-lane="polite">
      <span class="lr__wave" aria-hidden="true"><i></i><i></i><i></i></span>
      <span class="lr__saycap">reading</span>
      <span class="lr__saytxt">
        <span class="lr__sayone" data-lane="polite">Mail sent</span>
        <span class="lr__sayone" data-lane="alert">The payment was declined</span>
      </span>
    </div>
    <div class="lr__btns">
      <button class="lr__btn" type="button" data-lane="polite">Normal notice</button>
      <button class="lr__btn" type="button" data-lane="alert">Error notice</button>
    </div>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

$duration: $dur-quick;
$easing: $ease-pop;
$color: $subject-mint;

@include stage($stage-ink);

.lr {
  box-sizing: border-box;
  width: min(404px, 88vw);
  display: flex;
  flex-direction: column;
  gap: $sp-2;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-cream;
}

.lr__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: $sp-2;
}
.lr__col { display: flex; flex-direction: column; gap: $sp-1; }
.lr__tag {
  display: block;
  font-size: 9px;
  line-height: 14px;
  font-weight: 700;
  color: rgba(255, 247, 230, .5);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.lr__tag code {
  font-family: ui-monospace, "Consolas", monospace;
  font-size: 9px;
  color: rgba(255, 247, 230, .78);
}

.lr__card {
  box-sizing: border-box;
  display: flex;
  align-items: center;
  gap: $sp-2;
  margin: 0;
  padding: $sp-2 $sp-2;
  border: 2px solid rgba(255, 255, 255, .1);
  border-radius: $r-control;
  background: rgba(255, 255, 255, .06);
}
.lr__dot {
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: rgba(255, 247, 230, .28);
}
.lr__msg {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 11px;
  line-height: 18px;
  font-weight: 700;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
// 지금 읽히고 있는 줄만 테두리가 켜진다
.lr__col.is-live .lr__card { border-color: $color; background: rgba(76, 212, 166, .12); }
.lr__col.is-live .lr__dot { background: $color; }
.lr__col[data-lane="alert"].is-live .lr__card { border-color: $stage-orange; background: rgba(255, 77, 31, .14); }
.lr__col[data-lane="alert"].is-live .lr__dot { background: $stage-orange; }

.lr__say {
  box-sizing: border-box;
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-1 $sp-3;
  border-radius: $r-control;
  background: $subject-cream;
  color: $subject-ink;
}
.lr__wave { display: inline-flex; align-items: center; gap: $sp-1; flex: 0 0 auto; height: 14px; }
.lr__wave i {
  display: block;
  width: 3px;
  height: 14px;
  border-radius: $r-xs;
  background: $subject-blue;
  transform: scaleY(.3);
}
.lr__saycap {
  flex: 0 0 auto;
  font-size: 9px;
  line-height: 18px;
  font-weight: 700;
  color: rgba($stage-ink, .72);
}
.lr__saytxt { position: relative; display: block; flex: 1 1 auto; min-width: 0; height: 18px; }
.lr__sayone {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  opacity: 0;
  font-size: 12px;
  line-height: 18px;
  font-weight: 700;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.lr__say[data-lane="polite"] .lr__sayone[data-lane="polite"],
.lr__say[data-lane="alert"] .lr__sayone[data-lane="alert"] { opacity: 1; }
.lr__say[data-lane="alert"] .lr__sayone[data-lane="alert"] { color: $error; }

.lr__btns { display: flex; gap: $sp-2; }
.lr__btn {
  box-sizing: border-box;
  flex: 1 1 0;
  margin: 0;
  padding: $sp-1 $sp-2;
  border: 0;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .1);
  color: $subject-cream;
  font-family: inherit;
  font-size: 11px;
  line-height: 18px;
  font-weight: 700;
  cursor: pointer;
}
.lr__btn[data-lane="alert"] { background: $stage-orange; color: $subject-ink; }
.lr__btn:focus-visible { outline: 2px solid $color; outline-offset: 2px; }

// ── 자동 루프: 정중한 줄을 읽다가 오류가 들어와 읽던 문장을 끊고 넘어간다 ──
// 읽는 막대는 늘 움직이고 카드는 사라지지 않으므로 어느 프레임도 빈 화면이 아니다
.lr__wave i {
  animation-name: lr-wave;
  animation-duration: 600ms;
  animation-timing-function: ease-in-out;
  animation-iteration-count: infinite;
  animation-direction: alternate;
}
.lr__wave i:nth-child(1) { animation-delay: 0ms; }
.lr__wave i:nth-child(2) { animation-delay: -200ms; }
.lr__wave i:nth-child(3) { animation-delay: -400ms; }
@keyframes lr-wave {
  0%   { transform: scaleY(.24); }
  100% { transform: scaleY(1); }
}

// 켜진 줄과 읽히는 문장은 샘플 프레임 사이(45% · 89%)에서 끊어 바꾼다
.lr.is-demo .lr__card,
.lr.is-demo .lr__dot,
.lr.is-demo .lr__sayone {
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.lr.is-demo .lr__col[data-lane="polite"] .lr__card { animation-name: lr-on-polite; }
.lr.is-demo .lr__col[data-lane="polite"] .lr__dot { animation-name: lr-dot-polite; }
.lr.is-demo .lr__col[data-lane="alert"] .lr__card { animation-name: lr-on-alert; }
.lr.is-demo .lr__col[data-lane="alert"] .lr__dot { animation-name: lr-dot-alert; }
.lr.is-demo .lr__sayone[data-lane="polite"] { animation-name: lr-say-polite; }
.lr.is-demo .lr__sayone[data-lane="alert"] { animation-name: lr-say-alert; }

@keyframes lr-on-polite {
  0%   { border-color: $color; background-color: rgba(76, 212, 166, .12); }
  45%  { border-color: rgba(255, 255, 255, .1); background-color: rgba(255, 255, 255, .06); }
  89%  { border-color: $color; background-color: rgba(76, 212, 166, .12); }
  100% { border-color: $color; background-color: rgba(76, 212, 166, .12); }
}
@keyframes lr-dot-polite {
  0%   { background-color: $color; }
  45%  { background-color: rgba(255, 247, 230, .28); }
  89%  { background-color: $color; }
  100% { background-color: $color; }
}
@keyframes lr-on-alert {
  0%   { border-color: rgba(255, 255, 255, .1); background-color: rgba(255, 255, 255, .06); }
  45%  { border-color: $stage-orange; background-color: rgba(255, 77, 31, .14); }
  89%  { border-color: rgba(255, 255, 255, .1); background-color: rgba(255, 255, 255, .06); }
  100% { border-color: rgba(255, 255, 255, .1); background-color: rgba(255, 255, 255, .06); }
}
@keyframes lr-dot-alert {
  0%   { background-color: rgba(255, 247, 230, .28); }
  45%  { background-color: $stage-orange; }
  89%  { background-color: rgba(255, 247, 230, .28); }
  100% { background-color: rgba(255, 247, 230, .28); }
}
@keyframes lr-say-polite {
  0%   { opacity: 1; }
  45%  { opacity: 0; }
  89%  { opacity: 1; }
  100% { opacity: 1; }
}
@keyframes lr-say-alert {
  0%   { opacity: 0; }
  45%  { opacity: 1; }
  89%  { opacity: 0; }
  100% { opacity: 0; }
}

// 오류가 끼어드는 순간 그 카드가 한 번 튄다
.lr.is-demo .lr__col[data-lane="alert"] .lr__card {
  animation-name: lr-on-alert, lr-jolt;
  animation-duration: $dur-loop, $dur-loop;
  animation-timing-function: steps(1, end), $easing;
  animation-iteration-count: infinite, infinite;
}
@keyframes lr-jolt {
  0%, 45%   { transform: scale(1); }
  52%       { transform: scale(1.06); }
  62%       { transform: scale(1); }
  90%, 100% { transform: scale(1); }
}

@media (max-width: 340px) {
  .lr__card { padding: $sp-1; gap: $sp-1; }
  .lr__msg { font-size: 10px; line-height: 16px; }
  .lr__say { padding: 0 $sp-2; gap: $sp-1; }
  .lr__sayone { font-size: 11px; }
  .lr__btn { font-size: 10px; line-height: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  .lr__wave i,
  .lr.is-demo .lr__col,
  .lr.is-demo .lr__card,
  .lr.is-demo .lr__dot,
  .lr.is-demo .lr__sayone { animation: none !important; }
  .lr.is-demo .lr__sayone[data-lane="polite"] { opacity: 1; }
  .lr__wave i { transform: scaleY(.7); }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.lr {
  box-sizing: border-box;
  width: min(404px, 88vw);
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #fff7e6;
}

.lr__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.lr__col {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.lr__tag {
  display: block;
  font-size: 9px;
  line-height: 14px;
  font-weight: 700;
  color: rgba(255, 247, 230, 0.5);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lr__tag code {
  font-family: ui-monospace, "Consolas", monospace;
  font-size: 9px;
  color: rgba(255, 247, 230, 0.78);
}

.lr__card {
  box-sizing: border-box;
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 8px 8px;
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.06);
}

.lr__dot {
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: rgba(255, 247, 230, 0.28);
}

.lr__msg {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 11px;
  line-height: 18px;
  font-weight: 700;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lr__col.is-live .lr__card {
  border-color: #4cd4a6;
  background: rgba(76, 212, 166, 0.12);
}

.lr__col.is-live .lr__dot {
  background: #4cd4a6;
}

.lr__col[data-lane=alert].is-live .lr__card {
  border-color: #ff4d1f;
  background: rgba(255, 77, 31, 0.14);
}

.lr__col[data-lane=alert].is-live .lr__dot {
  background: #ff4d1f;
}

.lr__say {
  box-sizing: border-box;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 12px;
  border-radius: 12px;
  background: #fff7e6;
  color: #17141a;
}

.lr__wave {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  flex: 0 0 auto;
  height: 14px;
}

.lr__wave i {
  display: block;
  width: 3px;
  height: 14px;
  border-radius: 4px;
  background: #2f6df6;
  transform: scaleY(0.3);
}

.lr__saycap {
  flex: 0 0 auto;
  font-size: 9px;
  line-height: 18px;
  font-weight: 700;
  color: rgba(23, 20, 26, 0.72);
}

.lr__saytxt {
  position: relative;
  display: block;
  flex: 1 1 auto;
  min-width: 0;
  height: 18px;
}

.lr__sayone {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  opacity: 0;
  font-size: 12px;
  line-height: 18px;
  font-weight: 700;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lr__say[data-lane=polite] .lr__sayone[data-lane=polite],
.lr__say[data-lane=alert] .lr__sayone[data-lane=alert] {
  opacity: 1;
}

.lr__say[data-lane=alert] .lr__sayone[data-lane=alert] {
  color: #c2361a;
}

.lr__btns {
  display: flex;
  gap: 8px;
}

.lr__btn {
  box-sizing: border-box;
  flex: 1 1 0;
  margin: 0;
  padding: 4px 8px;
  border: 0;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.1);
  color: #fff7e6;
  font-family: inherit;
  font-size: 11px;
  line-height: 18px;
  font-weight: 700;
  cursor: pointer;
}

.lr__btn[data-lane=alert] {
  background: #ff4d1f;
  color: #17141a;
}

.lr__btn:focus-visible {
  outline: 2px solid #4cd4a6;
  outline-offset: 2px;
}

.lr__wave i {
  animation-name: lr-wave;
  animation-duration: 600ms;
  animation-timing-function: ease-in-out;
  animation-iteration-count: infinite;
  animation-direction: alternate;
}

.lr__wave i:nth-child(1) {
  animation-delay: 0ms;
}

.lr__wave i:nth-child(2) {
  animation-delay: -200ms;
}

.lr__wave i:nth-child(3) {
  animation-delay: -400ms;
}

@keyframes lr-wave {
  0% {
    transform: scaleY(0.24);
  }
  100% {
    transform: scaleY(1);
  }
}
.lr.is-demo .lr__card,
.lr.is-demo .lr__dot,
.lr.is-demo .lr__sayone {
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.lr.is-demo .lr__col[data-lane=polite] .lr__card {
  animation-name: lr-on-polite;
}

.lr.is-demo .lr__col[data-lane=polite] .lr__dot {
  animation-name: lr-dot-polite;
}

.lr.is-demo .lr__col[data-lane=alert] .lr__card {
  animation-name: lr-on-alert;
}

.lr.is-demo .lr__col[data-lane=alert] .lr__dot {
  animation-name: lr-dot-alert;
}

.lr.is-demo .lr__sayone[data-lane=polite] {
  animation-name: lr-say-polite;
}

.lr.is-demo .lr__sayone[data-lane=alert] {
  animation-name: lr-say-alert;
}

@keyframes lr-on-polite {
  0% {
    border-color: #4cd4a6;
    background-color: rgba(76, 212, 166, 0.12);
  }
  45% {
    border-color: rgba(255, 255, 255, 0.1);
    background-color: rgba(255, 255, 255, 0.06);
  }
  89% {
    border-color: #4cd4a6;
    background-color: rgba(76, 212, 166, 0.12);
  }
  100% {
    border-color: #4cd4a6;
    background-color: rgba(76, 212, 166, 0.12);
  }
}
@keyframes lr-dot-polite {
  0% {
    background-color: #4cd4a6;
  }
  45% {
    background-color: rgba(255, 247, 230, 0.28);
  }
  89% {
    background-color: #4cd4a6;
  }
  100% {
    background-color: #4cd4a6;
  }
}
@keyframes lr-on-alert {
  0% {
    border-color: rgba(255, 255, 255, 0.1);
    background-color: rgba(255, 255, 255, 0.06);
  }
  45% {
    border-color: #ff4d1f;
    background-color: rgba(255, 77, 31, 0.14);
  }
  89% {
    border-color: rgba(255, 255, 255, 0.1);
    background-color: rgba(255, 255, 255, 0.06);
  }
  100% {
    border-color: rgba(255, 255, 255, 0.1);
    background-color: rgba(255, 255, 255, 0.06);
  }
}
@keyframes lr-dot-alert {
  0% {
    background-color: rgba(255, 247, 230, 0.28);
  }
  45% {
    background-color: #ff4d1f;
  }
  89% {
    background-color: rgba(255, 247, 230, 0.28);
  }
  100% {
    background-color: rgba(255, 247, 230, 0.28);
  }
}
@keyframes lr-say-polite {
  0% {
    opacity: 1;
  }
  45% {
    opacity: 0;
  }
  89% {
    opacity: 1;
  }
  100% {
    opacity: 1;
  }
}
@keyframes lr-say-alert {
  0% {
    opacity: 0;
  }
  45% {
    opacity: 1;
  }
  89% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
.lr.is-demo .lr__col[data-lane=alert] .lr__card {
  animation-name: lr-on-alert, lr-jolt;
  animation-duration: 2s, 2s;
  animation-timing-function: steps(1, end), cubic-bezier(0.2, 1.4, 0.4, 1);
  animation-iteration-count: infinite, infinite;
}

@keyframes lr-jolt {
  0%, 45% {
    transform: scale(1);
  }
  52% {
    transform: scale(1.06);
  }
  62% {
    transform: scale(1);
  }
  90%, 100% {
    transform: scale(1);
  }
}
@media (max-width: 340px) {
  .lr__card {
    padding: 4px;
    gap: 4px;
  }
  .lr__msg {
    font-size: 10px;
    line-height: 16px;
  }
  .lr__say {
    padding: 0 8px;
    gap: 4px;
  }
  .lr__sayone {
    font-size: 11px;
  }
  .lr__btn {
    font-size: 10px;
    line-height: 16px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .lr__wave i,
  .lr.is-demo .lr__col,
  .lr.is-demo .lr__card,
  .lr.is-demo .lr__dot,
  .lr.is-demo .lr__sayone {
    animation: none !important;
  }
  .lr.is-demo .lr__sayone[data-lane=polite] {
    opacity: 1;
  }
  .lr__wave i {
    transform: scaleY(0.7);
  }
}

// 실제 동작: 같은 글자를 다시 넣어야 스크린리더가 한 번 더 읽는다. 오류만 assertive 줄로 보내 읽던 문장을 끊는다
var root = document.querySelector('.lr');
var cols = [].slice.call(document.querySelectorAll('.lr__col'));
var say = document.getElementById('lr-say');
function send(lane) {
  root.classList.remove('is-demo');
  var col = cols.filter(function (c) { return c.getAttribute('data-lane') === lane; })[0];
  cols.forEach(function (c) { c.classList.toggle('is-live', c === col); });
  say.setAttribute('data-lane', lane); // 화면에도 지금 읽히는 문장을 그대로 보여 준다
  var msg = col.querySelector('.lr__msg');
  var text = msg.textContent;
  msg.textContent = '';
  setTimeout(function () { msg.textContent = text; }, 40);
}
[].forEach.call(document.querySelectorAll('.lr__btn'), function (b) {
  b.addEventListener('click', function () { send(b.getAttribute('data-lane')); });
});

import { useEffect, useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./LiveRegionLanes.module.scss";

export type Lane = "polite" | "alert";
export type LiveRegionLanesProps = {
  messages?: Record<Lane, string>;
  tags?: Record<Lane, string>;
  laneLabels?: Record<Lane, string>;
  buttons?: Record<Lane, string>;
  sayCap?: string;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--easing"?: string; "--color"?: string };
const LANES: Lane[] = ["polite", "alert"];

export default function LiveRegionLanes({
  messages = { polite: "Mail sent", alert: "The payment was declined" },
  tags = { polite: "waits its turn", alert: "cuts in" },
  laneLabels = { polite: "Polite notification lane", alert: "Urgent notification lane" },
  buttons = { polite: "Normal notice", alert: "Error notice" },
  sayCap = "reading",
  easing = "cubic-bezier(.2,1.4,.4,1)",
  color = "#4cd4a6",
}: LiveRegionLanesProps) {
  const [demo, setDemo] = useState(true);
  const [lane, setLane] = useState<Lane>("polite");
  const [beat, setBeat] = useState(0);
  const [blank, setBlank] = useState<Lane | "">("");
  const timer = useRef<number[]>([0]);
  const vars: Vars = { "--easing": easing, "--color": color };

  useEffect(() => () => { clearTimeout((timer.current ?? [0])[0]); }, []);

  // 같은 글자를 비웠다 다시 넣어야 스크린리더가 한 번 더 읽는다
  function send(next: Lane) {
    setDemo(false);
    setLane(next);
    setBeat((v) => v + 1);
    setBlank(next);
    const t = timer.current ?? [0];
    clearTimeout(t[0]);
    t[0] = setTimeout(() => setBlank(""), 40) as unknown as number;
  }

  return (
    <div className={`${styles.lr} ${demo ? styles.isDemo : ""}`} style={vars}>
      <div className={styles.grid}>
        {LANES.map((l) => (
          <div key={l} className={`${styles.col} ${!demo && lane === l ? styles.isLive : ""}`} data-lane={l}>
            <span className={styles.tag}><code>{l === "alert" ? 'role="alert"' : 'role="status"'}</code> {tags[l]}</span>
            <p
              className={styles.card}
              role={l === "alert" ? "alert" : "status"}
              aria-live={l === "alert" ? "assertive" : "polite"}
              aria-atomic="true"
              aria-label={laneLabels[l]}
            >
              <span className={styles.dot} aria-hidden="true" />
              <span className={styles.msg} key={`${l}-${beat}`}>{blank === l ? "" : messages[l]}</span>
            </p>
          </div>
        ))}
      </div>
      <div className={styles.say} data-lane={demo ? undefined : lane}>
        <span className={styles.wave} aria-hidden="true"><i /><i /><i /></span>
        <span className={styles.saycap}>{sayCap}</span>
        <span className={styles.saytxt}>
          {LANES.map((l) => (
            <span key={l} className={styles.sayone} data-lane={l}>{messages[l]}</span>
          ))}
        </span>
      </div>
      <div className={styles.btns}>
        {LANES.map((l) => (
          <button key={l} className={styles.btn} type="button" data-lane={l} onClick={() => send(l)}>{buttons[l]}</button>
        ))}
      </div>
    </div>
  );
}