<canvas id="canvas" width="100" height="100"></canvas>
body {
  width: 100%;
  overflow: 'hidden';
}

#canvas {
  width: 100%;
  height: 100%;
}
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var width = window.innerWidth;
var height = window.innerHeight;
var dots = [];
var mousePos = {x: -20, y: -20};
var colors = ['#a8e6cf', '#dcedc1', '#ffd3b6', '#ffaaa5', '#ff8b94']

function Dot(x, y, color) {
  var _this = this;
  this.x = x;
  this.y = y;
  this.targetRadius = 3;
  this.radius = 3;
  this.color = color;
  
  this.draw = function() {
    var d = d2points(_this, mousePos);
    if (d < 100) _this.targetRadius = 3 + (100-d)/7;
    else _this.targetRadius = 3;
    _this.radius = _this.radius + (_this.targetRadius - _this.radius)*0.1;
    ctx.beginPath();
    ctx.arc(_this.x, _this.y, _this.radius, 0, 2 * Math.PI, false);
    ctx.fillStyle = _this.color;
    ctx.fill();
  }
}

function placeDots() {
  dots = [];
  var ci = 0;
  for (var x = 14; x < width; x = x+20) {
    for (var y = 14; y < height; y = y+20) {
      var d = new Dot(x, y, colors[ci%colors.length]);
      dots.push(d);
      ci++;
    }
  }
}

function drawDots() {
  for (var i = 0; i < dots.length; i++) {
    dots[i].draw();
  }
}

function resize() {
  width = window.innerWidth;
  height = window.innerHeight;
  canvas.width = width;
  canvas.height = height;
  placeDots();
}

function addListeners() {
  canvas.addEventListener('mousemove', mousemove);
  canvas.addEventListener('touchstart', touchmove);
  canvas.addEventListener('touchmove', touchmove);
  window.addEventListener('resize', resize);
  window.addEventListener('touchmove', function(e) {
                          e.preventDefault();
                          })
}

function mousemove(e) {
  mousePos.x = e.pageX;
  mousePos.y = e.pageY;
}

function touchmove(e) {
  	mousePos.y = e.targetTouches[0].pageY;
  	mousePos.x = e.targetTouches[0].pageX;
}

function loop() {
  ctx.clearRect(0,0,width,height);
  drawDots();
  requestAnimationFrame(loop);
}

function d2points(p1, p2)
{
  var xs = p2.x - p1.x;
  var xs = xs * xs;
  var ys = p2.y - p1.y;
  ys = ys * ys;
  return Math.sqrt( xs + ys );
}

resize();
addListeners();
loop();

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.