Imported from terminalskills/skills (skills/lottie/SKILL.md). Install upstream with npx skills add terminalskills/skills --skill lottie. Copyright stays with the author (Apache-2.0).

Lottie

Render After Effects animations exported as JSON. Lightweight, scalable, and interactive.

Setup

# Install lottie-web for vanilla JS/TS projects.
npm install lottie-web

Basic Playback

// src/lottie/player.ts — Load and play a Lottie animation in a DOM container.
// The animation JSON is typically exported from After Effects via Bodymovin.
import lottie, { AnimationItem } from "lottie-web";

export function playAnimation(
  container: HTMLElement,
  animationData: object
): AnimationItem {
  return lottie.loadAnimation({
    container,
    renderer: "svg", // "canvas" or "html" also available
    loop: true,
    autoplay: true,
    animationData,
  });
}

// Load from URL instead of inline data
export function playFromUrl(container: HTMLElement, path: string): AnimationItem {
  return lottie.loadAnimation({
    container,
    renderer: "svg",
    loop: true,
    autoplay: true,
    path, // URL to the JSON file
  });
}

Playback Controls

// src/lottie/controls.ts — Control animation playback: play, pause, seek, speed.
import type { AnimationItem } from "lottie-web";

export function setupControls(anim: AnimationItem) {
  // Play / Pause
  anim.play();
  anim.pause();
  anim.stop();

  // Go to specific frame (frame 30, and play)
  anim.goToAndPlay(30, true);

  // Go to specific frame and stop
  anim.goToAndStop(0, true);

  // Playback speed (2x)
  anim.setSpeed(2);

  // Play direction (-1 = reverse)
  anim.setDirection(-1);

  // Play only a segment (frames 10-50)
  anim.playSegments([10, 50], true);
}

Event Handling

// src/lottie/events.ts — Listen to animation lifecycle events for triggering
// UI updates, chaining animations, or tracking analytics.
import type { AnimationItem } from "lottie-web";

export function attachEvents(anim: AnimationItem) {
  anim.addEventListener("complete", () => {
    console.log("Animation completed");
  });

  anim.addEventListener("loopComplete", () => {
    console.log("Loop finished");
  });

  anim.addEventListener("enterFrame", (e) => {
    // Fires every frame — use sparingly
    const progress = (e as any).currentTime / anim.totalFrames;
    document.getElementById("progress")!.style.width = `${progress * 100}%`;
  });

  anim.addEventListener("DOMLoaded", () => {
    console.log("Animation DOM elements ready");
  });
}

React Integration

// src/components/LottiePlayer.tsx — React component wrapping lottie-web.
// Handles cleanup on unmount and exposes ref for external control.
import { useEffect, useRef } from "react";
import lottie, { AnimationItem } from "lottie-web";

interface Props {
  animationData: object;
  loop?: boolean;
  autoplay?: boolean;
  className?: string;
}

export function LottiePlayer({ animationData, loop = true, autoplay = true, className }: Props) {
  const containerRef = useRef<HTMLDivElement>(null);
  const animRef = useRef<AnimationItem | null>(null);

  useEffect(() => {
    if (!containerRef.current) return;

    animRef.current = lottie.loadAnimation({
      container: containerRef.current,
      renderer: "svg",
      loop,
      autoplay,
      animationData,
    });

    return () => {
      animRef.current?.destroy();
    };
  }, [animationData, loop, autoplay]);

  return <div ref={containerRef} className={className} />;
}

Dynamic Color Updates

// src/lottie/theme.ts — Modify colors inside a Lottie JSON before rendering.
// Useful for theming animations to match brand colors at runtime.
export function recolorAnimation(
  animationData: any,
  colorMap: Record<string, [number, number, number]>
): any {
  const data = JSON.parse(JSON.stringify(animationData));

  function walkShapes(shapes: any[]) {
    for (const shape of shapes) {
      if (shape.ty === "fl" && shape.c?.k) {
        const hex = rgbToHex(shape.c.k[0], shape.c.k[1], shape.c.k[2]);
        if (colorMap[hex]) {
          const [r, g, b] = colorMap[hex];
          shape.c.k = [r, g, b, 1];
        }
      }
      if (shape.it) walkShapes(shape.it);
    }
  }

  for (const layer of data.layers || []) {
    if (layer.shapes) walkShapes(layer.shapes);
  }

  return data;
}

function rgbToHex(r: number, g: number, b: number): string {
  return "#" + [r, g, b].map((v) => Math.round(v * 255).toString(16).padStart(2, "0")).join("");
}