CSS 实现钟表(同步本地时间)

// 获取当前时间，替换成表针角度的方法的一种实现
const getAngle = () => {
    const date = new Date()
    const h = date.getHours()
    const m = date.getMinutes()
    const s = date.getSeconds()
    return {
      angleh:
        Math.round(((h > 12 ? h - 12 : h) / 12) * 360) +
        Math.round((m / 60) * 30),
      anglem: Math.round((m / 60) * 360),
      angles: Math.round((s / 60) * 360),
    }
  }

<div className="roundAnim"

        style={{

          '--angles': getAngle().angles + 'deg',

          '--anglem': getAngle().anglem + 'deg',

          '--angleh': getAngle().angleh + 'deg',

        }}

>
    {/* 刻度 */}
    <div className="scale"></div>
    <div className="s"></div>
    <div className="m"></div>
    <div className="h"></div>
    <div className="point"></div>
</div>

// 表盘
.roundAnim {
  position: relative;
  width: 200px;
  height: 200px;
  border: 4px solid #000;
  border-radius: 50%;
}
// 表针容器
.roundAnim .s,
.roundAnim .m,
.roundAnim .h,
.roundAnim .point {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}
// 表针动画设置
.roundAnim .s {
  transform: rotate(var(--angles));
  animation: propertyRotateS 60s infinite steps(60);
}
.roundAnim .m {
  transform: rotate(var(--anglem));
  animation: propertyRotateM 3600s infinite steps(360);
}
.roundAnim .h {
  transform: rotate(var(--angleh));
  animation: propertyRotateH 86400s infinite steps(86400);
}
// 表针中心点样式
.roundAnim .point::before {
  content: ' ';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 10px;
  height: 10px;
  background-color: #000;
  border-radius: 50%;
}
// 秒针样式
.roundAnim .s::before {
  content: ' ';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 2px;
  height: 160px;
  background: linear-gradient(
    180deg,
    #000 0%,
    #000 50%,
    transparent 50%,
    transparent 100%
  );
  border-radius: 2px;
}
// 分针样式
.roundAnim .m::before {
  content: ' ';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 3px;
  height: 120px;
  background: linear-gradient(
    180deg,
    #000 0%,
    #000 50%,
    transparent 50%,
    transparent 100%
  );
  border-radius: 2px;
}
// 时针样式
.roundAnim .h::before {
  content: ' ';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%); // 针的一半透明不显示
  width: 5px;
  height: 100px;
  background: linear-gradient(
    180deg,
    #000 0%,
    #000 50%,
    transparent 50%,
    transparent 100%
  );
  border-radius: 2px;
}

// 表盘刻度--网上找的
.scale {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 100%;
  height: 100%;
  background: repeating-conic-gradient(
      from -0.5deg,
      #333 0 1deg,
      transparent 0deg 30deg
    ),
    repeating-conic-gradient(from -0.5deg, #ccc 0 1deg, transparent 0deg 6deg);
  border-radius: 50%;
  -webkit-mask: radial-gradient(transparent 88px, red 0);
}

// 动画

@keyframes propertyRotateS {
  0% {
　　tranform: rotate(var(--angles));
  }
  100% {
　　tranform: rotate(calc(360deg+var(--angles)));
　}
}

@keyframes propertyRotateM {
  0% {
　　tranform: rotate(var(--anglem));
  }
  100% {
　　tranform: rotate(calc(360deg+var(--anglem)));
　}
}

@keyframes propertyRotateH {
  0% {
　　tranform: rotate(var(--angleh));
  }
  100% {
　　tranform: rotate(calc(360deg+var(--angleh)));
　}
}

效果：