New York State D3 Counties Highlight & Hover

<!DOCTYPE html>
<meta charset="utf-8">
  <style>
    @import url(styles.css);
  </style>
    <script src="//d3js.org/d3.v3.min.js"></script>
    <script src="//d3js.org/queue.v1.min.js"></script>
<body>

<div id="map_container">
  <script>
    var mw = 800; // map container width
    var mh = 600; // map container height
    var toolTipVisible = true;
    var svg = d3.select("#map_container")
        .append("svg")
        .attr({"width": mw, "height": mh});
    var data;
    var ny;

// Define the div for the tooltip
    var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

queue()
    .defer(d3.csv, "highlight.csv", data)
    .await(ready);

function ready(error, data) {
      if (error) throw error;

d3.xml("ny.svg", "image/svg+xml", function(error, xml) { /* embed the SVG map */
        if (error) throw error;

var svgMap = xml.getElementsByTagName("g")[0]; /* set svgMap to root g */
        ny = svg.node().appendChild(svgMap); /* ny map */

svg.selectAll("#counties").selectAll("polygon")
          .on("click", handleClick)
          .on("mouseover", handleMouseOver)
          .on("mouseout", handleMouseOut);

svg.selectAll("#counties").selectAll("path")
          .on("click", handleClick)
          .on("mouseover", handleMouseOver)
          .on("mouseout", handleMouseOut);

d3.map(data, function(d) {
          console.log(d.county)
          d3.select("#"+d.county).attr("class", "highlight");
        });

});
    }

function handleClick(d, i){
      id = d3.select(this).attr('id');
    }

function handleMouseOver(d){
      if (d3.select(this).classed("active")) return;
      /* no need to change class when county is already selected */

if (!d3.select(this).classed("highlight")){
        d3.select(this).attr("class", "hover");
      }

if(toolTipVisible){
        div.transition()
            .duration(200)
            .style("opacity", .9);
        div .html(d3.select(this).attr('id').replace("_", " "))
            .style("left", (d3.event.pageX) + "px")
            .style("top", (d3.event.pageY - 5) + "px");
      }
    }

function handleMouseOut(d){
      if (d3.select(this).classed("active")) return;

if (!d3.select(this).classed("highlight")){
        d3.select(this).attr("class", "st0");
      }

div.transition()
          .duration(200)
          .style("opacity", 0);
      div .html('')
          .style("left", "0px")
          .style("top", "0px");
    }

</script>
</body>
</html>

https://d3js.org/d3.v3.min.js

https://d3js.org/queue.v1.min.js