SVG Animation

Crisp, lightweight, infinitely scalable vector motion — ideal for icons, illustrations, logos, and data marks. SVG can be animated three ways: CSS (declarative, simple), SMIL (

<animate>

inside the SVG), and JS (GSAP/Web Animations, for control and morphing). Choose per task; the techniques below say which.

When to use

Stroke "draw-on" of icons, illustrations, signatures, maps
Shape/path morphing and animated icon state changes (menu ↔ close, play ↔ pause)
Moving an element along a path (motion path)
Animated gradients, filters (glow, displacement), and animated logos

Core techniques

Stroke draw-on (the staple)

Draw the dash array as long as the path, offset it fully (invisible), then animate the offset to 0.

css

.path {
  stroke-dasharray: var(--len);
  stroke-dashoffset: var(--len);
  animation: draw 1.4s ease forwards;
}
@keyframes draw { to { stroke-dashoffset: 0; } }

Getting the length:

JS (most reliable):

const len = path.getTotalLength(); path.style.setProperty("--len", len);

No-JS trick: set
```
pathLength="1"
```
on the
```
<path>
```
, then
```
stroke-dasharray: 1; stroke-dashoffset: 1;
```
and animate to
```
0
```
. This normalizes any path to a 0–1 length so no measurement is needed.

Reverse (erase) by animating offset from 0 back to

len

. Stagger multiple paths with

animation-delay

. Direction of drawing follows the path's point order; reverse it in the editor or negate the offset sign if it draws "backwards".

Morphing one path into another

Paths interpolate point-by-point, so a naive morph requires both

attributes to have the same number and type of commands. Two robust approaches:

GSAP MorphSVG (free as of GSAP 3.12) — handles mismatched point counts automatically and finds a good mapping:

gsap.registerPlugin(MorphSVGPlugin);
gsap.to("#start", { morphSVG: "#end", duration: 0.8, ease: "power2.inOut" });
// Convert any shape to a morph-able path:
MorphSVGPlugin.convertToPath("circle, rect, ellipse, line, polygon");

Flubber (small standalone lib) — generates interpolators without GSAP, good with React/Framer Motion:

import { interpolate } from "flubber";
const interpolator = interpolate(pathA, pathB, { maxSegmentLength: 2 });
// interpolator(0) === pathA, interpolator(1) === pathB; feed t into a tween.

For hand-authored morphs (icon toggles), keep both paths with identical command structure and animate

directly via Web Animations or CSS (

is animatable in modern browsers via

path("...")

Motion along a path

GSAP MotionPath (preferred — control, alignment, scrub):

gsap.registerPlugin(MotionPathPlugin);
gsap.to("#rocket", {
  duration: 4, repeat: -1, ease: "none",
  motionPath: { path: "#track", align: "#track", autoRotate: true, alignOrigin: [0.5, 0.5] },
});

autoRotate: true

orients the object to the path tangent;

align

makes coordinates relative to the path element.

SMIL (no JS):

svg

<path id="track" d="M10,80 C40,10 120,10 150,80" fill="none"/>
<circle r="6" fill="#3b82f6">
  <animateMotion dur="3s" repeatCount="indefinite" rotate="auto">
    <mpath href="#track"/>
  </animateMotion>
</circle>

CSS offset-path (modern, declarative):

offset-path: path("M10,80 C..."); animation: move 3s linear infinite;

with

@keyframes move { to { offset-distance: 100%; } }

and

offset-rotate: auto

Animated gradients and filters

Gradients: animate

gradientTransform

or stop offsets. A sheen sweep:

svg

<linearGradient id="sheen">
  <stop offset="0%"  stop-color="#fff" stop-opacity="0"/>
  <stop offset="50%" stop-color="#fff" stop-opacity=".8"/>
  <stop offset="100%" stop-color="#fff" stop-opacity="0"/>
  <animateTransform attributeName="gradientTransform" type="translate"
    from="-1 0" to="1 0" dur="2s" repeatCount="indefinite"/>
</linearGradient>

Filters: animate

feDisplacementMap

scale

for gooey/wobble,

feGaussianBlur

stdDeviation

for focus pulls, or

feColorMatrix

feFlood

for glow. Filters are paint-heavy — animate sparingly and prefer

transform

opacity

where possible.

Implementation choice (pick fast)

Need	Use
Single declarative draw/fade	CSS
Self-contained, no JS bundle	SMIL ( `<animate*>` in the SVG)
Coordinated, scrubbable, scroll-tied	GSAP
Mismatched-point morph	GSAP MorphSVG or Flubber
Path following with rotation	GSAP MotionPath / CSS offset-path

SMIL caveat: not supported in IE/old Edge and historically deprecation-flagged; for max reach or scroll-syncing, prefer CSS or JS. SMIL is still fine for self-contained icon assets in evergreen browsers.

Authoring and optimization

Build/clean with SVGO: keep
```
viewBox
```
, drop editor metadata, but disable
```
cleanupIds
```
/
```
removeViewBox
```
and any plugin that renames IDs you reference from CSS/JS/SMIL. Disable
```
mergePaths
```
and
```
convertShapeToPath
```
if you animate individual sub-paths or shapes.
Inline the SVG in the DOM (not
```
<img src>
```
) so CSS/JS can reach its internals;
```
<img>
```
-embedded SVG can only self-animate via internal SMIL/CSS.
Set explicit
```
viewBox
```
and avoid fixed
```
width
```
/
```
height
```
so the asset scales fluidly.
For draw-on, ensure paths are actual strokes (
```
fill:none; stroke:...
```
), not filled outlines — dashoffset only affects strokes.
Respect
```
prefers-reduced-motion
```
: gate looping/large motion; keep a static final state.

Deliver & verify (standalone HTML)

Packaged helper (
scripts/
):
scripts/seek-shot.sh anim.html 0 1.5 3
freezes the
?t=N
harness and screenshots each moment;
scripts/contact-sheet.sh sheet.png frame-*.png
tiles them for one-glance review. See
scripts/README.md
.

For a self-contained icon/logo/draw-on the deliverable is one HTML file that opens directly in a browser — inline the SVG in the markup, drive the animation with one mechanism, no build step. One file is the right tier for a vector asset; don't reach for a bundler.

Output contract:

One
```
.html
```
file: inline
```
<svg>
```
, plus CSS
```
@keyframes
```
/ a
```
<script>
```
with GSAP from CDN / SMIL
```
<animate*>
```
— pick one driver.
Include the seek harness matching that driver so any moment can be frozen for a screenshot.

Seek harness — freeze an exact moment.

?t=N

seeks and pauses so a screenshot lands on a still frame. Use the mechanism that matches how the SVG animates:

html

<script>
  const t = new URLSearchParams(location.search).get("t");
  if (t !== null) {
    const N = parseFloat(t);
    // SMIL: pause the SVG's own clock and scrub it
    const svg = document.querySelector("svg");
    svg.pauseAnimations(); svg.setCurrentTime(N);
    // CSS @keyframes draw-on: el.style.animationDelay=(-N)+"s"; el.style.animationPlayState="paused";
    // GSAP timeline: tl.pause(); tl.seek(N);
  }
  window.__ready = true;
</script>

Verify loop — render → freeze → screenshot → check: open the file at start / mid / end (

?t=0

?t=<dur/2>

?t=<dur>

), screenshot each, and check fidelity (stroke draws in the right direction, morph endpoints clean) plus artifacts (path clipped by

viewBox

, stroke vanishing from a stale dashoffset, FOUC, jank at the morph seam). Any headless tool works:

bash

npx playwright screenshot --wait-for-timeout=500 "file://$PWD/icon.html?t=0.7" frame-mid.png

Before you finish:

Opens standalone — no console errors, inline SVG reachable, CDN (if any) loads.
The seek mechanism for your driver freezes a deterministic frame.
Screenshotted at start / mid / end — matches the brief, no clipping or off-
```
viewBox
```
strokes.
```
prefers-reduced-motion
```
honored — looping/large motion gated, static final state kept.
Easing is intentional —
```
ease
```
/GSAP ease chosen on purpose, no accidental
```
linear
```
draw-on.

Reference files

```
references/svg-techniques.md
```
— full dashoffset math and
```
getTotalLength
```
gotchas, the
```
pathLength="1"
```
normalization, GSAP MorphSVG vs Flubber decision guide with code, an icon-toggle morph (hamburger↔close), MotionPath/offset-path details, SMIL-vs-CSS-vs-JS tradeoffs, and an SVGO config tuned for animation.

svg-animation

NPX Install

Tags

SKILL.md Content