09Word swap typing

<main class="stage">
  <p class="swap">
    <span class="swap__prefix">Built just for </span><span class="swap__slot"><span class="swap__word swap__word--1">Designers</span><span class="swap__word swap__word--2">Developers</span><span class="swap__word swap__word--3">Marketers</span></span><span class="swap__suffix"> — try it</span>
  </p>
</main>

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

$duration: $dur-loop;                      // 단어 세 개가 차례로 도는 전체 루프
$easing: $ease-out;                        // 문장 색·굵기 톤
$color: $subject-blue;                     // 바뀌는 단어 색

@include stage($stage-ink);

.swap {
  margin: 0;
  font-weight: 700; font-size: clamp(17px, 4.8vw, 27px); line-height: 1.5; font-family: inherit;
  color: $subject-cream;

  &__slot { position: relative; display: inline-flex; vertical-align: bottom; }
  &__word {
    display: inline-block;
    overflow: hidden;
    white-space: nowrap;
    width: 0;
    border-right: .1em solid $color;
    color: $color;

    &--1 { animation: w1 $duration linear infinite; }
    &--2 { position: absolute; left: 0; top: 0; animation: w2 $duration linear infinite; }
    &--3 { position: absolute; left: 0; top: 0; animation: w3 $duration linear infinite; }
  }
}

@keyframes w1 {
  0%        { width: 0; animation-timing-function: steps(4, end); }
  8%        { width: var(--full, 4ch); }
  30%       { width: var(--full, 4ch); animation-timing-function: steps(4, end); }
  38%, 100% { width: 0; }
}
@keyframes w2 {
  0%, 40%   { width: 0; animation-timing-function: steps(3, end); }
  46%       { width: var(--full, 4ch); }
  68%       { width: var(--full, 4ch); animation-timing-function: steps(3, end); }
  74%, 100% { width: 0; }
}
@keyframes w3 {
  0%, 74%   { width: 0; animation-timing-function: steps(3, end); }
  80%       { width: var(--full, 4ch); }
  96%       { width: var(--full, 4ch); animation-timing-function: steps(3, end); }
  100%      { width: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .swap__word            { animation: none; }
  .swap__word--1         { width: var(--full, 4ch); }
  .swap__word--2,
  .swap__word--3         { width: 0; opacity: 0; }
}

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);
}

.swap {
  margin: 0;
  font-weight: 700;
  font-size: clamp(17px, 4.8vw, 27px);
  line-height: 1.5;
  font-family: inherit;
  color: #fff7e6;
}
.swap__slot {
  position: relative;
  display: inline-flex;
  vertical-align: bottom;
}
.swap__word {
  display: inline-block;
  overflow: hidden;
  white-space: nowrap;
  width: 0;
  border-right: 0.1em solid #2f6df6;
  color: #2f6df6;
}
.swap__word--1 {
  animation: w1 2s linear infinite;
}
.swap__word--2 {
  position: absolute;
  left: 0;
  top: 0;
  animation: w2 2s linear infinite;
}
.swap__word--3 {
  position: absolute;
  left: 0;
  top: 0;
  animation: w3 2s linear infinite;
}

@keyframes w1 {
  0% {
    width: 0;
    animation-timing-function: steps(4, end);
  }
  8% {
    width: var(--full, 4ch);
  }
  30% {
    width: var(--full, 4ch);
    animation-timing-function: steps(4, end);
  }
  38%, 100% {
    width: 0;
  }
}
@keyframes w2 {
  0%, 40% {
    width: 0;
    animation-timing-function: steps(3, end);
  }
  46% {
    width: var(--full, 4ch);
  }
  68% {
    width: var(--full, 4ch);
    animation-timing-function: steps(3, end);
  }
  74%, 100% {
    width: 0;
  }
}
@keyframes w3 {
  0%, 74% {
    width: 0;
    animation-timing-function: steps(3, end);
  }
  80% {
    width: var(--full, 4ch);
  }
  96% {
    width: var(--full, 4ch);
    animation-timing-function: steps(3, end);
  }
  100% {
    width: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .swap__word {
    animation: none;
  }
  .swap__word--1 {
    width: var(--full, 4ch);
  }
  .swap__word--2,
  .swap__word--3 {
    width: 0;
    opacity: 0;
  }
}

(function () {
  var cv = document.createElement('canvas').getContext('2d');
  document.querySelectorAll('.swap__word').forEach(function (el) {
    cv.font = getComputedStyle(el).font;
    el.style.setProperty('--full', Math.ceil(cv.measureText(el.textContent).width) + 'px');
  });
})();

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

export type WordSwapProps = {
  prefix: string;
  words: [string, string, string];
  suffix: string;
  /** 단어 세 개가 차례로 도는 전체 루프 (기본 2000ms) */
  duration?: number;
  color?: string;
};

export default function WordSwap({ prefix, words, suffix, duration = 2000, color = "#2f6df6" }: WordSwapProps) {
  const r1 = useRef<HTMLSpanElement | null>(null);
  const r2 = useRef<HTMLSpanElement | null>(null);
  const r3 = useRef<HTMLSpanElement | null>(null);
  useEffect(() => {
    const cv = document.createElement("canvas").getContext("2d");
    if (!cv) return;
    [r1, r2, r3].forEach((r) => {
      const el = r.current;
      if (!el) return;
      cv.font = getComputedStyle(el).font;
      el.style.setProperty("--full", Math.ceil(cv.measureText(el.textContent || "").width) + "px");
    });
  }, [words]);
  const vars = { "--duration": `${duration}ms`, "--color": color } as CSSProperties;
  const e = (s: string) => ({ "--easing": `steps(${s.length}, end)` } as CSSProperties);
  return (
    <p className={styles.swap} style={vars}>
      <span className={styles.prefix}>{prefix} </span>
      <span className={styles.slot}>
        <span ref={r1} className={`${styles.word} ${styles.w1}`} style={e(words[0])}>{words[0]}</span>
        <span ref={r2} className={`${styles.word} ${styles.w2}`} style={e(words[1])}>{words[1]}</span>
        <span ref={r3} className={`${styles.word} ${styles.w3}`} style={e(words[2])}>{words[2]}</span>
      </span>
      <span className={styles.suffix}> {suffix}</span>
    </p>
  );
}