# Path trace

Subtle web animation sketch from [https://mighil.com/animations](https://mighil.com/animations).

- **Live demo:** https://mighil.com/animations/path-trace
- **Standalone HTML:** https://mighil.com/animations/path-trace?download=1
- **This file:** https://mighil.com/animations/path-trace/path-trace.md
- **Technique:** `stroke`

## What it does

One stroke draws the path, then stops.

## Instructions for AI / coding agents

Implement this micro-interaction in the user's stack (vanilla HTML, React, Vue, Svelte, etc.).

1. Use the **HTML** as the DOM structure (adapt JSX/templates as needed; keep class names and ids).
2. Include the **Theme** CSS (or map the same variables into the host design system). It switches light/dark with `prefers-color-scheme`.
3. Apply the **CSS** as-is when possible. It uses `var(--text-color)`, `var(--heading-color)`, `var(--background-color)`, etc. from the theme so both modes work.
4. Run the **JavaScript** after the markup mounts. Prefer `DOMContentLoaded` or a framework `useEffect` / `onMount`.
5. Keep motion respectful of `prefers-reduced-motion` if the snippet already checks it.
6. Do not depend on mighil.com runtime or fonts. Theme variables are enough for color.
7. If porting to a component, expose the interactive root via a ref and preserve accessibility attributes (`aria-*`, `role`, `button` types).

## Theme (auto light / dark)

```css
/* Auto light / dark — follows prefers-color-scheme */
:root{
  color-scheme: light dark;
  --text-color: hsl(0, 0%, 18%);
  --heading-color: hsl(0, 0%, 18%);
  --background-color: hsl(0, 0%, 99%);
  --bg-color: hsl(0, 0%, 99%);
  --link-color: hsl(0, 0%, 18%);
  --visited-color: hsl(0, 0%, 18%);
  --blockquote-color: hsl(0, 0%, 18%);
  --code-bg-color: hsl(0, 0%, 95%);
  --code-color: hsl(0, 0%, 18%);
  --sub-color: hsl(0, 0%, 29%);
}
@media (prefers-color-scheme: dark){
:root{
  --text-color: hsl(35, 25%, 85%);
  --heading-color: hsl(35.2, 32.6%, 82.5%);
  --background-color: hsl(60, 2.2%, 8.8%);
  --bg-color: hsl(60, 2.2%, 8.8%);
  --link-color: hsl(34.7, 55.3%, 79.8%);
  --visited-color: hsla(34.7, 55.3%, 79.8%, 0.85);
  --blockquote-color: hsl(35, 30%, 75%);
  --code-bg-color: hsl(30, 5%, 7.8%);
  --code-color: limegreen;
  --sub-color: hsla(34.7, 24.7%, 84.9%, 0.78);
}
}
```

## HTML

```html
<svg class="trace-svg" id="trace-svg" viewBox="0 0 220 56" aria-hidden="true">
        <path d="M8 40 C40 8, 70 48, 110 22 S180 8, 212 34"/>
      </svg>
```

## CSS

```css
.trace-svg{width:min(100%,300px);height:72px;overflow:visible;color:inherit}

.trace-svg path{
  fill:none;stroke:currentColor;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round;
  opacity:.85;
}
```

## JavaScript

```js
// Path trace
  const traceSvg = document.getElementById('trace-svg');
  function runTrace() {
    if (!traceSvg) return;
    const path = traceSvg.querySelector('path');
    if (!path) return;
    const len = path.getTotalLength();
    path.style.transition = 'none';
    path.style.strokeDasharray = String(len);
    path.style.strokeDashoffset = String(len);
    void path.getBoundingClientRect();
    if (reduce) {
      path.style.strokeDashoffset = '0';
      return;
    }
    requestAnimationFrame(() => {
      path.style.transition = 'stroke-dashoffset 1.4s cubic-bezier(.22, 1, .36, 1)';
      path.style.strokeDashoffset = '0';
    });
  }
  runTrace();

document.querySelectorAll('[data-act]').forEach((btn) => {
    btn.addEventListener('click', (e) => {
      e.stopPropagation();
      const act = btn.getAttribute('data-act');
      if (act === 'trace') runTrace();
    });
  });
```

---

_Source: https://mighil.com/animations/path-trace_