JS1k: The JavaScript code golfing competition

var b=requestAnimationFrame,d=Math,e='length',f='splice',g=2*d.PI,h,j,k,l,m,n,o=[],p=a.width,q=a.height,r,s,t=(w,z)=>d.random()*(z-w)+w,u=class{constructor(w,{x:z=t(0,p),y:A=q}={},B=t(0,360),C=t(50,60)){for(h=this,j=t(0,g),k=15*d.cos(t(0,g)),h.R=w,h.p={x:z,y:A},h.v={x:w?t(-3,3):d.cos(j)*k,y:w?t(-10,-4):d.sin(j)*k},h.S=w?0.999:t(0,0.05)+0.93,h.g=w?0.01:0.2,h.r=w?1:0.92,h.s=3,h.h=B,h.b=C,h.P=[],m=3;m--;)h.P.push({x:z,y:A})}u(w){if(h=this,n=h.P.pop(),c.beginPath(),c.moveTo(n.x,n.y),c.lineTo(h.p.x,h.p.y),c.lineWidth=h.s,c.strokeStyle=`hsla(${h.h},100%,${h.b}%,1)`,c.stroke(),h.P.unshift({x:h.p.x,y:h.p.y}),h.v.x*=h.r,h.v.y*=h.r,h.v.y+=h.g,h.p.x+=h.v.x,h.p.y+=h.v.y,h.s*=h.S,1>=h.s||h.p.x>p||0>h.p.x||h.p.y>q||0>h.p.y)o[f](w,1);else if(h.R&&h.p.y<=0.5*q&&0.08>=t(0,1)){for(l=t(0,10)+100,s=0;s<l;s+=1)o.push(new u(!1,h.p,h.h,h.b));o[f](w,1)}}},v=()=>{for(c.fillStyle='#000',c.fillRect(0,0,p,q),r=o[e];r--;)o[r].u(r);5>o.filter(w=>w.R)[e]&&o.push(new u(!0)),b(v)};b(v)

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

var raf = requestAnimationFrame
var Maths = Math
var length = 'length'
var splice = 'splice'
var TAU = Maths.PI * 2;

var that
var angle
var speed
var count
var positionCount
var lastPosition
var elements = [];
var cw = a.width;
var ch = a.height;
var x
var i
var random = (min, max) => Maths.random() * (max - min) + min

// isRocket = R
// position = p
// positions = P
// velocity = v
// size = s
// hue = h
// brightness = b
// shrink = S
// gravity = g
// resistance = r

var Particle = class {
  constructor(
    isRocket,
    {
      x = random(0, cw),
      y = ch
    } = {},
    hue = random(0, 360),
    brightness = random(50, 60)
  ) {
    that = this
    angle = random(0, TAU);
    speed = Maths.cos(random(0, TAU)) * 15;
    that.R = isRocket
    that.p = {x, y};
    that.v = {
      x: isRocket ? random(-3, 3) : (Maths.cos(angle) * speed),
      y: isRocket ? random(-10, -4) : (Maths.sin(angle) * speed)
    };
    that.S = isRocket ? 0.999 : (random(0, 0.05) + 0.93);
    that.g = isRocket ? 0.01 : 0.2;
    that.r = isRocket ? 1 : 0.92;
    that.s = 3;
    that.h = hue
    that.b = brightness
    that.P = [];
    positionCount = 3;
    while (positionCount--) {
        that.P.push({x, y});
    }
  }
  u (index) {
    that = this
    lastPosition = that.P.pop()
    c.beginPath();
    c.moveTo(lastPosition.x, lastPosition.y);
    c.lineTo(that.p.x, that.p.y);
    c.lineWidth = that.s;
    c.strokeStyle = `hsla(${that.h},100%,${that.b}%,1)`;
    c.stroke();
    that.P.unshift({ x: that.p.x, y: that.p.y });
    that.v.x *= that.r;
    that.v.y *= that.r;
    that.v.y += that.g;
    that.p.x += that.v.x;
    that.p.y += that.v.y;
    that.s *= that.S;
    if (
      that.s <= 1
      || that.p.x > cw || that.p.x < 0
      || that.p.y > ch || that.p.y < 0
    ) {
      elements[splice](index, 1);
    }
    else if (that.R) {
      if (that.p.y <= ch * 0.5 && random(0, 1) <= 0.08) {
        count = random(0, 10) + 100;
        for (i = 0; i < count; i += 1) {
          elements.push(new Particle(false, that.p, that.h, that.b));
        }
        elements[splice](index, 1);
      }
    }
  }
}

var update = () => {
  c.fillStyle = '#000';
  c.fillRect(0, 0, cw, ch);
  x = elements[length];
  while (x--) {
      elements[x].u(x);
  }
  if (elements.filter(x => x.R)[length] < 5) {
      elements.push(new Particle(true));
  }
  raf(update)
}

raf(update)