Pretty minified version of https://github.com/tkazec/demos/blob/master/js1k/min/firehearts.min.js

gistfile1.js

(function () {
	var e = this.requestAnimationFrame || this.webkitRequestAnimationFrame || this.mozRequestAnimationFrame || this.msRequestAnimationFrame || this.oRequestAnimationFrame || function (g) { setTimeout(g, 1E3 / 60) },
		f = Math,
		l = f.PI,
		m = f.floor,
		n = f.random,
		o = c.width = 960,
		r = c.height = 540,
		u = [],
		v = 0;

	function w(g, p, d, x, i, j, h) {
		for (var q = [], k = "#" + "F20,F0F,F6B,C18,408,800".split(",")[m(6 * n())]; j--;) {
			var s = 2 * l * n(),
				t = x * n();
			
			q.push({
				x: g,
				y: p,
				a: t * f.cos(s),
				b: t * f.sin(s),
				d: 0.97 + (i - 100) / 1E3,
				c: d + m(6 * n()),
				e: k
			})
		}
		
		setTimeout(function () {
			u = u.concat(q);
			v--
		}, h * (1E3 / 60))
	}
	
	(function y() {
		if (!u.length && !v) for (var p = v = m(6 * n()); p--;) w(130 + m(701 * n()), 130 + m(151 * n()), 5 + m(16 * n()), 4 + m(7 * n()), 70 + m(40 * n()), 50 + m(201 * n()), m(150 * n()));
		
		u.forEach(function (d, p) {
			d.x += d.a;
			d.y += d.b;
			d.a *= d.d;
			d.b *= d.d;
			d.y += 1.1;
			
			a.fillStyle = !m(4 * n()) ? "rgba(256,256,256,.8)" : d.e;
			
			var i = d.x,
				j = d.y,
				h = d.c,
				q = 0.48 * h,
				k = 0.24 * h,
				h = 0.336 * h;
			
			a.beginPath();
			a.moveTo(i - q, j);
			a.lineTo(i, j + q);
			a.arc(i + k, j - k, h, 0.25 * l, 1.25 * l, !0);
			a.arc(i - k, j - k, h, 1.75 * l, 0.75 * l, !0);
			a.fill();
			
			0.1 > (d.c *= d.d) && u.splice(p, 1)
		});
		
		a.fillStyle = "rgba(0,0,0,.3)";
		a.fillRect(0, 0, o, r);
		
		e(y)
	})();
	
	c.onclick = function (g) {
		v++;
		w(g.pageX - this.offsetLeft, g.pageY - this.offsetTop, 5 + m(16 * n()), 4 + m(7 * n()), 70 + m(40 * n()), 50 + m(201 * n()), 0)
	};
	
	b.onkeypress = function () {
		[
			[480, 350],
			[430, 300],
			[530, 300],
			[380, 250],
			[580, 250],
			[360, 200],
			[480, 200],
			[600, 200],
			[410, 160],
			[550, 160]
		].forEach(function (g) {
			v++;
			w(g[0], g[1], 50, 3, 50, 100, 0)
		})
	}
})()