colorz.js

var width = 660,
    height = 600;

var color = d3.scale.linear()
    .domain([0, width/4, width/4 * 2, width/4 * 3, width])
    .range(["#fb000f", "#6e00fb", "#00fbec", "#8dfb00", "#fb3c00"])
    .interpolate(d3.interpolateHsl);    
                
var svg = d3.select("#colorz").append("svg")
    .attr("width", width)
    .attr("height", height)
    .attr("viewBox", "0 0 660 600")
    .attr("perserveAspectRatio", "xMinYMid")
    .on("mousemove", mousemove);

var data = d3.range(320);   

svg.selectAll("circle")
    .data(data)
  .enter().append("circle")
    .attr("cx", function(d, i) { return (((i % 20) * 38) + 10); })
    .attr("cy", function(d, i) { return ((Math.floor(i / 20) * 38) + 10); })
    .attr("r", 3)
    .style("fill", function(d, i) { return d3.rgb(color(((i % 20) * 38) + 10)).darker(Math.floor(i / 20)*(1/4)).toString(); })
  .transition()
    .duration(1500)
    .attr("r", 18.5)
    .each("end", function() {
      d3.select(this)
        .transition()
          .duration(1500)
          .attr("r", 3); 
    });
                  
function mousemove() {
  var m = d3.mouse(this),
      x = m[0],
      y = m[1];

  svg.append("circle")
    .transition()
      .duration(0)
      .attr("r", 10)
      .attr("transform", "translate(" + x + "," + y + ")scale(2)")
      .style("fill", d3.rgb(color(x)).darker((d3.max([0,y-10]) / width) * 3.75).toString())
      .each("end", function() {
        d3.select(this)
          .transition()
            .duration(1500)
            .attr("transform", "translate(" + (x + ((Math.round(Math.random() * 1) * 2 - 1) * 
              Math.floor((Math.random()*60)+1))) + "," + (y + ((Math.round(Math.random()*1) * 2 - 1) * 
              Math.floor((Math.random()*60)+1))) + ")")
            .attr("r", 1e-6)
            .remove();
      });
}

// making viz responsive for smaller windows
var chart = $("#colorz svg"),
    aspect = chart.width() / chart.height(),
    container = chart.parent();

$(window).on("resize", function() {
    var targetWidth = container.width();
    chart.attr("width", targetWidth);
    chart.attr("height", Math.round(targetWidth / aspect));
}).trigger("resize");