test/event/mouse-test.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>HTML Mouse Test</title>
<body>
<script src="../../d3.js"></script>
<script>

var body = d3.select("body");

var div = body.append("div")
    .style("width", "1000px")
    .style("height", "500px")
    .style("border", "solid black 1px")
    .style("cursor", "crosshair");

var span = body.append("span");

d3.select(window).on("mousemove", function() {
  span.text(d3.mouse(div[0][0]));
});

</script>