04Avatar Where a Name Value Computes Initials Before Lazy Loading

<main class="stage">
<div class="lai is-demo" id="lai">
  <ul class="lai__list" id="laiList"></ul>
  <button type="button" class="lai__btn" id="laiBtn">Load photos</button>
</div>
</main>

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

// 이름 값 → 이니셜 계산(자리표시자) + 글자코드 합 해시(배지 색) + 행 인덱스 값(등장 지연).
// 세 계산 겹이 함께 실제 지연 로딩의 "먼저 보여주고 나중에 바뀐다"를 만든다.

$duration: $dur-base;
$easing: $ease-pop;
$color: $subject-pink;

@include stage($stage-paper);

.lai {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  width: min(100%, 240px);
}

.lai__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
  width: 100%;
}

.lai__row {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-1 $sp-2;
  border-radius: $r-sm;
  background: rgba(23, 20, 26, .04);
}

.lai__avatar {
  position: relative;
  flex: 0 0 auto;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  overflow: hidden;
}

.lai__row--a { background: rgba(255, 158, 187, .3); color: darken($subject-pink, 25%); }
.lai__row--b { background: rgba(76, 212, 166, .3); color: darken($subject-mint, 30%); }
.lai__row--c { background: rgba(185, 160, 255, .3); color: darken($subject-lilac, 28%); }
.lai__row--d { background: rgba(110, 200, 255, .3); color: darken($subject-sky, 30%); }

.lai__initials {
  font-weight: 700;
  font-size: 13px;
  transition: opacity $dur-quick $ease-out;
}

.lai__photo {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  opacity: 0;
  transform: scale(.6);
  transition: transform $dur-enter $easing, opacity $dur-base $ease-out;
  background: conic-gradient(from 120deg, $subject-blue, $subject-mint, $subject-pink, $subject-blue);
}

.lai__avatar--loaded .lai__initials { opacity: 0; }
.lai__avatar--loaded .lai__photo { opacity: 1; transform: scale(1); }

.lai__name {
  font-size: 13px;
  font-weight: 600;
  color: $stage-ink;
}

.lai__btn {
  border: none;
  border-radius: $r-pill;
  padding: $sp-1 $sp-3;
  background: $color;
  color: $stage-ink;
  font-weight: 700;
  font-size: 12px;
  cursor: pointer;
}

@media (max-width: 340px) {
  .lai__avatar { width: 28px; height: 28px; }
  .lai__row { padding: $sp-1 $sp-2; gap: $sp-1; }
}

@media (prefers-reduced-motion: reduce) {
  .lai__photo, .lai__initials { transition: none !important; }
}

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

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

.lai {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  width: min(100%, 240px);
}

.lai__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
}

.lai__row {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 8px;
  border-radius: 8px;
  background: rgba(23, 20, 26, 0.04);
}

.lai__avatar {
  position: relative;
  flex: 0 0 auto;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  overflow: hidden;
}

.lai__row--a {
  background: rgba(255, 158, 187, 0.3);
  color: rgb(100%, 11.9607843137%, 38.2817869416%);
}

.lai__row--b {
  background: rgba(76, 212, 166, 0.3);
  color: rgb(10.2543720191%, 42.6868044515%, 31.7170111288%);
}

.lai__row--c {
  background: rgba(185, 160, 255, 0.3);
  color: rgb(31.2858617131%, 6.7450980392%, 100%);
}

.lai__row--d {
  background: rgba(110, 200, 255, 0.3);
  color: rgb(0%, 51.6024340771%, 83.137254902%);
}

.lai__initials {
  font-weight: 700;
  font-size: 13px;
  transition: opacity 220ms ease-out;
}

.lai__photo {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  opacity: 0;
  transform: scale(0.6);
  transition: transform 600ms cubic-bezier(0.2, 1.4, 0.4, 1), opacity 300ms ease-out;
  background: conic-gradient(from 120deg, #2f6df6, #4cd4a6, #ff9ebb, #2f6df6);
}

.lai__avatar--loaded .lai__initials {
  opacity: 0;
}

.lai__avatar--loaded .lai__photo {
  opacity: 1;
  transform: scale(1);
}

.lai__name {
  font-size: 13px;
  font-weight: 600;
  color: #17141a;
}

.lai__btn {
  border: none;
  border-radius: 999px;
  padding: 4px 12px;
  background: #ff9ebb;
  color: #17141a;
  font-weight: 700;
  font-size: 12px;
  cursor: pointer;
}

@media (max-width: 340px) {
  .lai__avatar {
    width: 28px;
    height: 28px;
  }
  .lai__row {
    padding: 4px 8px;
    gap: 4px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .lai__photo, .lai__initials {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('lai');
  var list = document.getElementById('laiList');
  var btn = document.getElementById('laiBtn');
  var NAMES = ['Kim Haneul', 'Lee Doyun', 'Park Seojun'];
  var PALETTE = ['lai__row--a', 'lai__row--b', 'lai__row--c', 'lai__row--d'];
  var ROW_STAGGER_MS = 260;
  var LOAD_BASE_MS = 320;
  var CYCLE_GAP_MS = 2400;

  // 계산 겹 1: 이름 문자열에서 이니셜 두 글자를 잘라낸다.
  function getInitials(name) { return name.slice(0, 2); }

  // 계산 겹 2: 이름 글자 코드값을 모두 더한 뒤 팔레트 길이로 나눈 나머지로 배지 색을 고른다(해시).
  function colorHashClass(name) {
    var sum = 0;
    for (var i = 0; i < name.length; i += 1) { sum += name.charCodeAt(i); }
    return PALETTE[sum % PALETTE.length];
  }

  var rows = NAMES.map(function (name, i) {
    var li = document.createElement('li');
    li.className = 'lai__row';
    li.innerHTML =
      '<span class="lai__avatar ' + colorHashClass(name) + '" data-idx="' + i + '">' +
        '<span class="lai__initials">' + getInitials(name) + '</span>' +
        '<span class="lai__photo"></span>' +
      '</span>' +
      '<span class="lai__name">' + name + '</span>';
    list.appendChild(li);
    return li;
  });

  function reset() {
    rows.forEach(function (li) { li.querySelector('.lai__avatar').classList.remove('lai__avatar--loaded'); });
  }

  // 계산 겹 3: 목록 위치(행 인덱스) 값으로 등장 지연 시간을 계산해 순서대로 사진이 나타난다.
  var timers = [];
  function loadPhotos() {
    reset();
    rows.forEach(function (li, i) {
      var t = setTimeout(function () {
        li.querySelector('.lai__avatar').classList.add('lai__avatar--loaded');
      }, LOAD_BASE_MS + i * ROW_STAGGER_MS);
      timers.push(t);
    });
  }

  function clearTimers() { timers.forEach(clearTimeout); timers = []; }

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    clearTimers();
    loadPhotos();
  });

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var autoplayTimer = null;
  if (reduce) {
    root.classList.remove('is-demo');
    rows.forEach(function (li) { li.querySelector('.lai__avatar').classList.add('lai__avatar--loaded'); });
  } else {
    (function loop() {
      clearTimers();
      loadPhotos();
      autoplayTimer = setTimeout(function () {
        if (!root.classList.contains('is-demo')) { return; }
        reset();
        setTimeout(function () {
          if (root.classList.contains('is-demo')) { loop(); }
        }, 500);
      }, LOAD_BASE_MS + rows.length * ROW_STAGGER_MS + CYCLE_GAP_MS);
    })();
  }
})();

import { useEffect, useRef, useState, useCallback } from "react";
import styles from "./AvatarInitialsFallback.module.scss";

// 이름 값 → 이니셜 계산(자리표시자) + 글자코드 합 해시(배지 색) + 행 인덱스 값(등장 지연).
const NAMES = ["김하늘", "이도윤", "박서준"];
const PALETTE = ["lai__row--a", "lai__row--b", "lai__row--c", "lai__row--d"];
const ROW_STAGGER_MS = 260;
const LOAD_BASE_MS = 320;
const CYCLE_GAP_MS = 2400;

function getInitials(name: string): string {
  return name.slice(0, 2);
}

function colorHashClass(name: string): string {
  let sum = 0;
  for (let i = 0; i < name.length; i += 1) { sum += name.charCodeAt(i); }
  return PALETTE[sum % PALETTE.length];
}

type Box<T> = { current: T };
function useBox<T>(initial: T): Box<T> {
  return useRef(initial) as unknown as Box<T>;
}

export default function AvatarInitialsFallback() {
  const rootRef = useRef<HTMLDivElement>(null);
  const [demo, setDemo] = useState(true);
  const [loaded, setLoaded] = useState<boolean[]>(NAMES.map(() => false));
  const timersRef = useBox<number[]>([]);
  const loopTimerRef = useRef<number | null>(null);

  const clearTimers = useCallback(() => {
    timersRef.current.forEach((t) => window.clearTimeout(t));
    timersRef.current = [];
  }, [timersRef]);

  const loadPhotos = useCallback(() => {
    setLoaded(NAMES.map(() => false));
    NAMES.forEach((_, i) => {
      const t = window.setTimeout(() => {
        setLoaded((prev) => prev.map((v, j) => (j === i ? true : v)));
      }, LOAD_BASE_MS + i * ROW_STAGGER_MS);
      timersRef.current.push(t);
    });
  }, [timersRef]);

  const onClickLoad = useCallback(() => {
    setDemo(false);
    clearTimers();
    loadPhotos();
  }, [clearTimers, loadPhotos]);

  useEffect(() => {
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (reduce) {
      setDemo(false);
      setLoaded(NAMES.map(() => true));
      return;
    }
    let cancelled = false;
    function loop() {
      if (cancelled) { return; }
      clearTimers();
      loadPhotos();
      loopTimerRef.current = window.setTimeout(() => {
        if (cancelled || !rootRef.current?.classList.contains(styles["is-demo"])) { return; }
        setLoaded(NAMES.map(() => false));
        loopTimerRef.current = window.setTimeout(() => {
          if (!cancelled && rootRef.current?.classList.contains(styles["is-demo"])) { loop(); }
        }, 500);
      }, LOAD_BASE_MS + NAMES.length * ROW_STAGGER_MS + CYCLE_GAP_MS);
    }
    loop();
    return () => {
      cancelled = true;
      clearTimers();
      if (loopTimerRef.current !== null) { window.clearTimeout(loopTimerRef.current); }
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <main className={styles.stage}>
      <div ref={rootRef} className={`${styles.lai} ${demo ? styles["is-demo"] : ""}`}>
        <ul className={styles["lai__list"]}>
          {NAMES.map((name, i) => (
            <li key={name} className={styles["lai__row"]}>
              <span className={`${styles["lai__avatar"]} ${styles[colorHashClass(name)]} ${loaded[i] ? styles["lai__avatar--loaded"] : ""}`}>
                <span className={styles["lai__initials"]}>{getInitials(name)}</span>
                <span className={styles["lai__photo"]} />
              </span>
              <span className={styles["lai__name"]}>{name}</span>
            </li>
          ))}
        </ul>
        <button type="button" className={styles["lai__btn"]} onClick={onClickLoad}>사진 불러오기</button>
      </div>
    </main>
  );
}