Ch. 12, Fig. 5 - D3.js in Action

This is the code for Chapter 12, Figure 5 from D3.js in Action which requires a touch interface (or emulator) to see any effect. This example uses data from d3.touches() to create SVG circles at each touch location as well as draw lines between each touch location.

<html>
<head>
  <title>D3 in Action Chapter 12 - Example 3</title>
  <meta charset="utf-8" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
</head>
<style>
  body, html {
    width:100%;
    height:100%;
  }
  #vizcontainer {
    width:100%;
    height:100%;
  }
  svg {
    width: 100%;
    height: 100%;
  }
</style>
<body>
<div id="vizcontainer">
  <svg></svg>
</div>
</body>
  <footer>
    
<script>
     d3.select("svg").on("touchstart", touchStatus);
     d3.select("svg").on("touchmove", touchStatus);

var touchColor = d3.scale.linear().domain([0, 10]).range(["pink", "darkred"])

function touchStatus() {
       d3.event.preventDefault();
       d3.event.stopPropagation();
       d = d3.touches(this);
       d3.select("svg").selectAll("circle").data(d).enter().append("circle").attr("r", 75).style("fill", function(d, i) {
         return touchColor(i)
       });

d3.select("svg").selectAll("circle").data(d).exit().remove();

d3.select("svg").selectAll("circle").attr("cx", function(d) {
         return d[0]
       }).attr("cy", function(d) {
         return d[1]
       });

d3.select("svg").selectAll("line").attr("x1", function(d) {
           return d.source[0]
         }).attr("y1", function(d) {
           return d.source[1]
         }).attr("x2", function(d) {
           return d.target[0]
         }).attr("y2", function(d) {
           return d.target[1]
         })

}
       d3.select("svg").selectAll("line").data(l).exit().remove();

}
</script>
  </footer>

</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js