✨moving cat

JS ⟩ browser ⟩ animation ⟩ example ⟩ moving cat

keep moving an image by updating its .style.left property.

💾 程式

• replit ⟩ moving cat

const {log} = console;
const {cos} = Math;

// ⭐️ import
import { $ } from './js/ext/Node_ext.js';         // Node extension
// --------------------------------------------------------------------

let cat = $("img");
let angle = Math.PI / 2;

// ⭐️ 1. request first frame
requestAnimationFrame(animate);

// render loop
// - t1: current timestamp (in ms)
// - t0: last timestamp
function animate(t1, t0) {
    
    if (!t0) t0 = t1;
    
    // ⭐️ 2. update animation
    angle += (t1 - t0) * 0.001;        // 1/sec = 57.3 °/sec
    cat.style.left = cos(angle) * 100 + "px";
    
    // ⭐️ 3. request next frame
    requestAnimationFrame(t2 => animate(t2, t1));
}

🗺️ 圖表

👥 相關

• .requestAnimationFrame()

📗 參考

• Eloquent JS ⟩ DOM ⟩ Positioning & Animating