02Auto thousands separator

<main class="stage">
  <div class="counter is-demo">
    <span class="counter__num" aria-hidden="true"></span>
    <span class="counter__sr">12,483</span>
    <span class="counter__label">Views</span>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;
$easing: $ease-out;
$color: $subject-ink;                                // 숫자 색 (노란 무대 위 대비)

@include stage($stage-yellow);

// 천 단위(k)와 나머지(n)를 각각 다른 정수 커스텀 속성으로 나눠 센다
@property --k {
  syntax: '<integer>';
  initial-value: 0;
  inherits: false;
}
@property --n {
  syntax: '<integer>';
  initial-value: 0;
  inherits: false;
}

// 나머지(n)는 항상 세 자리로 채워야 "12,003" 이 "12,3" 이 되지 않는다
@counter-style padded-3 {
  system: numeric;
  symbols: '0' '1' '2' '3' '4' '5' '6' '7' '8' '9';
  suffix: '';
  pad: 3 '0';
}

.counter {
  text-align: center;

  &__num {
    --k: 0;
    --n: 0;
    counter-reset: k var(--k) n var(--n);
    display: block;
    font-weight: 800; font-size: clamp(30px, 9vw, 52px); line-height: 1; font-family: inherit;
    font-variant-numeric: tabular-nums;
    color: $color;

    &::before { content: counter(k) "," counter(n, padded-3); }
  }

  &__sr {
    position: absolute;
    width: 1px; height: 1px;
    overflow: hidden;
    clip-path: inset(50%);
    white-space: nowrap;
  }

  &__label {
    display: block;
    margin-top: clamp(6px, 2vw, 10px);
    font-weight: 600; font-size: clamp(12px, 3.4vw, 15px); line-height: 1; font-family: inherit;
    color: rgba($subject-ink, .72);                  // 흐린 글자는 알파 .72 하한 — 옐로 면 위 6.06:1
  }
}

.counter.is-demo .counter__num {
  animation: thousands-up $duration $easing infinite;
}

@keyframes thousands-up {
  0%   { --k: 0;  --n: 0; }
  65%  { --k: 12; --n: 483; }
  100% { --k: 12; --n: 483; }
}

@media (prefers-reduced-motion: reduce) {
  .counter.is-demo .counter__num { animation: none; --k: 12; --n: 483; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

@property --k {
  syntax: "<integer>";
  initial-value: 0;
  inherits: false;
}
@property --n {
  syntax: "<integer>";
  initial-value: 0;
  inherits: false;
}
@counter-style padded-3 {
  system: numeric;
  symbols: "0" "1" "2" "3" "4" "5" "6" "7" "8" "9";
  suffix: "";
  pad: 3 "0";
}
.counter {
  text-align: center;
}
.counter__num {
  --k: 0;
  --n: 0;
  counter-reset: k var(--k) n var(--n);
  display: block;
  font-weight: 800;
  font-size: clamp(30px, 9vw, 52px);
  line-height: 1;
  font-family: inherit;
  font-variant-numeric: tabular-nums;
  color: #17141a;
}
.counter__num::before {
  content: counter(k) "," counter(n, padded-3);
}
.counter__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
.counter__label {
  display: block;
  margin-top: clamp(6px, 2vw, 10px);
  font-weight: 600;
  font-size: clamp(12px, 3.4vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: rgba(23, 20, 26, 0.72);
}

.counter.is-demo .counter__num {
  animation: thousands-up 2s ease-out infinite;
}

@keyframes thousands-up {
  0% {
    --k: 0;
    --n: 0;
  }
  65% {
    --k: 12;
    --n: 483;
  }
  100% {
    --k: 12;
    --n: 483;
  }
}
@media (prefers-reduced-motion: reduce) {
  .counter.is-demo .counter__num {
    animation: none;
    --k: 12;
    --n: 483;
  }
}

import type { CSSProperties } from "react";
import styles from "./ThousandsSeparatorCounter.module.scss";

export type ThousandsSeparatorCounterProps = {
  /** 12483 처럼 콤마 없는 정수 */
  value: number;
  label: string;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & {
  "--duration"?: string; "--easing"?: string; "--color"?: string;
  "--k-target"?: number; "--n-target"?: number;
};

export default function ThousandsSeparatorCounter({
  value, label, duration = 2000, easing = "ease-out", color = "#17141a",
}: ThousandsSeparatorCounterProps) {
  const k = Math.floor(value / 1000);
  const n = value % 1000;
  const vars: Vars = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
    "--k-target": k,
    "--n-target": n,
  };

  return (
    <div className={styles.counter} style={vars}>
      <span className={styles.num} aria-hidden="true" />
      <span className={styles.sr}>{value.toLocaleString()}</span>
      <span className={styles.label}>{label}</span>
    </div>
  );
}