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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              //step one: changed bubble and bubbles to be single and lots, because I couldn't easily see what was bubble and what was Bubble and what was bubbles.
//step two: changed to using height and width instead of hard-coded integers, create conditionals for large heights
//step three: convert to svg
//step four: incorporated PR to use elapsed time to calculate animation, https://github.com/sdras/JS-stroll/pull/2 + performs better

var svg = document.createElementNS("http://www.w3.org/2000/svg", "svg"),
    svgNS = svg.namespaceURI,
    vbx = document.createElementNS(svgNS, "viewBox"),
    width = window.innerWidth,
    height = window.innerHeight,
    gravity = 0.00009,
    friction = 0.000001,
    lots = [],
    prevTime;

document.body.appendChild(svg);
document.body.style.background = '#222';
svg.setAttribute("viewBox", "0 0 " + width + " " + height);
svg.setAttribute("width", width);
svg.setAttribute("height", height);

Bubble.prototype = {
  init: function (x, y, vx, vy) {
    this.x = x;
    this.y = y;
    this.vx = vx;
    this.vy = vy;
  },
  update: function (dt) {
    // friction opposes the direction of velocity
    var acceleration = -Math.sign(this.vx) * friction;
    // distance = velocity * time + 0.5 * acceleration * (time ^ 2)
    this.x += this.vx * dt + 0.5 * acceleration * (dt ^ 2);
    this.y += this.vy * dt + 0.5 * gravity * (dt ^ 2);
    // velocity = velocity + acceleration * time
    this.vy += gravity * dt;
    this.vx += acceleration * dt;
    this.circ.setAttribute("cx", this.x);
    this.circ.setAttribute("cy", this.y);
    this.circ.setAttribute("stroke", "rgba(1,146,190," + this.opacity + ")");
  }
};

for (var i = 0; i < 150; i++) {
  setTimeout(function () {
    var single = new Bubble(0.5+Math.random()*0.5, 5 + Math.random()*10);
    initBubble(single);
    lots.push(single);
  }, i*18);
}

function Bubble(opacity, radius) {
  this.init(width/2, height/2, 0, 0);
  this.opacity = opacity;
  this.radius = radius;
  var circ = document.createElementNS(svgNS, "circle");
  svg.appendChild(circ);
  circ.setAttribute("r", this.radius);
  circ.setAttribute("fill", "none");
  circ.setAttribute("stroke-width", "1px");
  this.circ = circ;
}

function initBubble(single) {
  single.init(width/2, height/2, -0.05 + Math.random()*0.1, -0.1 + Math.random()*0.1);
}

(function animate(currentTime) {
  var dt;
  requestAnimationFrame(animate);
  if (!prevTime) {
    // only save previous time
    prevTime = currentTime;
    return;
  } else {
    // calculate the time difference between frames
    // it has to be less than 25ms because of switching between tabs
    dt = Math.min(currentTime - prevTime, 25);
    prevTime = currentTime;
  }
  for (var i = 0; i < lots.length; i++) {
    lots[i].update(dt);

    //if the height is small, just let it start over when it gets to the bottom, otherwise, at 3/4 (so that there aren't big gaps)
    if (height < 500) {
      if (lots[i].y > height) {
        initBubble(lots[i]);
      }
    } else {
      if (lots[i].y > height*0.85) {
        initBubble(lots[i]);
      }
    }
  }
}());
            
          
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