Loading

<button class="btn-loading" type="button" data-busy="Saving…">
  <span>Save changes</span>
</button>

.btn-loading {
  --btn-bg: #7c5cff;
  --btn-fg: #ffffff;
  --btn-font: inherit;
  --btn-size: 15px;
  --btn-weight: 600;
  --btn-px: 22px;
  --btn-py: 11px;
  --btn-w: auto;
  --btn-h: auto;
  --btn-bw: 0px;
  --btn-line: #8b6cff;
  --btn-radius: 10px;
  --btn-shadow: none;
  --btn-speed: 180ms;
}

.btn-loading {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  box-sizing: border-box;
  width: var(--btn-w);
  height: var(--btn-h);
  padding: var(--btn-py) var(--btn-px);
  font-family: var(--btn-font);
  font-size: var(--btn-size);
  font-weight: var(--btn-weight);
  line-height: 1.2;
  color: var(--btn-fg);
  background: var(--btn-bg);
  border: var(--btn-bw) solid var(--btn-line);
  border-radius: var(--btn-radius);
  box-shadow: var(--btn-shadow);
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: all var(--btn-speed) ease;
}

.btn-loading:focus-visible {
  outline: 2px solid var(--btn-bg);
  outline-offset: 2px;
}

.btn-loading:disabled {
  opacity: 0.5;
  pointer-events: none;
}

.btn-loading__icon {
  width: 1.15em;
  height: 1.15em;
  flex-shrink: 0;
}

.btn-loading[data-state=busy]::before {
  content: "";
  width: 1em;
  height: 1em;
  box-sizing: border-box;
  border-style: solid;
  border-width: 2px;
  border-color: currentColor transparent currentColor currentColor;
  border-radius: 50%;
  animation: btn-spin 0.7s linear infinite;
}

.btn-loading[data-state=busy] {
  opacity: 0.8;
  cursor: progress;
}

@keyframes btn-spin {
  to { transform: rotate(360deg); }
}

@media (prefers-reduced-motion: reduce) {
  .btn-loading,
  .btn-loading::before {
    animation: none !important;
    transition: none !important;
  }
}

document.querySelectorAll(".btn-loading").forEach((el) => {
  const label = el.querySelector("span");
  const idle = label.textContent;
  const { busy, done } = el.dataset;
  let timer = 0;
  const show = (state, text, next, wait) => {
    el.dataset.state = state;
    label.textContent = text;
    timer = window.setTimeout(next, wait);
  };
  const reset = () => {
    delete el.dataset.state;
    label.textContent = idle;
  };
  const finish = () => (done ? show("done", done, reset, 1800) : reset());
  const start = () => {
    if (el.dataset.state) return;
    // Demo timer: run your real work here and call finish() when it ends.
    if (busy) show("busy", busy, finish, 1500);
    else finish();
  };
  el.addEventListener("click", start);
  return () => {
    clearTimeout(timer);
    el.removeEventListener("click", start);
  };
});

import { useEffect, useRef } from "react";
import type React from "react";
import "./loading.css"; // the CSS tab

function attach(el: HTMLElement) {
  const label = el.querySelector("span") as HTMLElement;
  const idle = label.textContent;
  const { busy, done } = el.dataset;
  let timer = 0;
  const show = (state: string, text: string, next: () => void, wait: number) => {
    el.dataset.state = state;
    label.textContent = text;
    timer = window.setTimeout(next, wait);
  };
  const reset = () => {
    delete el.dataset.state;
    label.textContent = idle;
  };
  const finish = () => (done ? show("done", done, reset, 1800) : reset());
  const start = () => {
    if (el.dataset.state) return;
    // Demo timer: run your real work here and call finish() when it ends.
    if (busy) show("busy", busy, finish, 1500);
    else finish();
  };
  el.addEventListener("click", start);
  return () => {
    clearTimeout(timer);
    el.removeEventListener("click", start);
  };
}

export function BtnLoading({ children = "Save changes", ...props }: React.ComponentProps<"button">) {
  const ref = useRef<HTMLButtonElement>(null);
  useEffect(() => attach(ref.current!), []);

  return (
    <button className="btn-loading" type="button" data-busy="Saving…" ref={ref} {...props}>
      <span>{children}</span>
    </button>
  );
}

<button class="btn-loading relative inline-flex items-center justify-center gap-[0.5em] [box-sizing:border-box] [padding:11px_22px] [font-family:inherit] text-[15px] font-[600] [line-height:1.2] text-[#ffffff] bg-[#7c5cff] [border:0px_solid_#8b6cff] rounded-[10px] [box-shadow:none] cursor-pointer no-underline whitespace-nowrap [transition:all_180ms_ease] focus-visible:[outline:2px_solid_#7c5cff] focus-visible:[outline-offset:2px] disabled:[opacity:0.5] disabled:[pointer-events:none] [&[data-state=busy]]:before:content-[''] [&[data-state=busy]]:before:w-[1em] [&[data-state=busy]]:before:h-[1em] [&[data-state=busy]]:before:[box-sizing:border-box] [&[data-state=busy]]:before:[border-style:solid] [&[data-state=busy]]:before:[border-width:2px] [&[data-state=busy]]:before:[border-color:currentColor_transparent_currentColor_currentColor] [&[data-state=busy]]:before:rounded-[50%] [&[data-state=busy]]:before:[animation:btn-spin_0.7s_linear_infinite] [&[data-state=busy]]:[opacity:0.8] [&[data-state=busy]]:[cursor:progress] motion-reduce:[transition:none!important] motion-reduce:before:[animation:none!important]" type="button" data-busy="Saving…">
  <span>Save changes</span>
</button>

<!-- A class cannot hold keyframes: keep this in your CSS. -->
<style>
@keyframes btn-spin {
  to { transform: rotate(360deg); }
}
</style>

<!-- Needs the script from the JS tab. -->