var duration = 15 * 1000; var animationEnd = Date.now() + duration; var defaults = { startVelocity: 30, spread: 360, ticks: 60, zIndex: 0 }; function randomInRange(min, max) { return Math.random() * (max - min) + min; } var interval = setInterval(function() { var timeLeft = animationEnd - Date.now(); if (timeLeft <= 0) { return clearInterval(interval); } var particleCount = 50 * (timeLeft / duration); // since particles fall down, start a bit higher than random confetti({ ...defaults, particleCount, origin: { x: randomInRange(0.1, 0.3), y: Math.random() - 0.2 } }); confetti({ ...defaults, particleCount, origin: { x: randomInRange(0.7, 0.9), y: Math.random() - 0.2 } }); }, 250);