Stacked Bar Chart with Tooltip by D3 v4

This is stacked bar chart done by D3.

Based on D3 Stacked Bar Chart by Mike Bostock https://bl.ocks.org/mbostock/3886208 Tooltip code based on D3 Stacked Bar Chart with Tooltips by Michael Stanaland /mstanaland/6100713

The data source comes from data.gov

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
body {
   background-color: lightgrey;
}

svg {
    width: 100%;
    height: 100%;
    position: center;
}

.rect:hover {
   fill: yellow;
}

.tooltip {
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    position: absolute;
    display: none;
    width: auto;
    height: auto;
    background: none repeat scroll 0 0 red;
    border: 0 none;
    border-radius: 8px 8px 8px 8px;
    box-shadow: -3px 3px 15px #888888;
    color: blue;
    font: 12px sans-serif;
    padding: 5px;
    text-align: center;
}

</style>
<body>
  <svg width="960" height="500"></svg>
</body>
<script>
var margin = {top: 30, right: 30, bottom: 50, left: 30};
var width = 960 - margin.left - margin.right;
var height = 500 - margin.top - margin.bottom;

var g = d3.select("svg")
        //.append("svg")
        //.attr("width", width)
        //.attr("height", height)
        .append("g")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var x0 = d3.scaleBand()
    .rangeRound([0, width])
    .paddingInner(0.2);

var x1 = d3.scaleBand()
    .padding(0.1);

var y = d3.scaleLinear()
    .rangeRound([height, 0]);

g.append("g")
    .selectAll("g")
    .data(data)
    .enter().append("g")
    .attr("transform", function(d) { return "translate(" + x0(d.Age_Group) + ",0)"; })
    .selectAll("rect")
    .data(function(d) { return keys.map(function(key) { return {key: key, value: d[key]}; }); })
    .enter().append("rect").attr("class", "rect")
    .attr("x", function(d) { return x1(d.key); })
    .attr("y", function(d) { return y(d.value); })
    .attr("width", x1.bandwidth())
    .attr("height", function(d) { return height - y(d.value); })
    .attr("fill", function(d) { return z(d.key); })
    .on("mouseover", function() { tooltip.style("display", null); })
    .on("mousemove", function(d) {
      var xPosition = d3.mouse(this)[0] + 5;
      var yPosition = d3.mouse(this)[1] - 5;
      tooltip
      .attr("transform", "translate(" + xPosition + "," + yPosition + ")")
      .style("display", "inline")
      .select("text").text(d.value);
      })
    .on("mouseout", function() { tooltip.style("display", "none"); });
    
  g.append("g")
    .attr("class", "axis")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x0))
    .selectAll("text")  
    .style("text-anchor", "end")
    .attr("dx", "-.1em")
    .attr("transform", "rotate(-45)" );
    
  g.append("g")
    .attr("class", "axis")
    .call(d3.axisLeft(y).ticks(null, ".0%"))
    .append("text")
    .attr("x", 2)
    .attr("y", y(y.ticks().pop()) + 0.5)
    .attr("dy", "0.32em")
    .attr("fill", "#000")
    .attr("font-weight", "bold")
    .attr("text-anchor", "start")
    .text("Percentage");
    
  var legend = g.append("g")
      .attr("font-family", "sans-serif")
      .attr("font-size", 10)
      .attr("text-anchor", "end")
      .selectAll("g")
      .data(keys.slice().reverse())
      .enter().append("g")
      .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });
      
  legend.append("rect")
      .attr("x", width - 19)
      .attr("width", 19)
      .attr("height", 19)
      .attr("fill", z);

legend.append("text")
      .attr("x", width - 24)
      .attr("y", 9.5)
      .attr("dy", "0.32em")
      .text(function(d) { return d; });
});

// Prep the tooltip bits, initial display is hidden
  var tooltip = d3.select("body").append("svg")
    .attr("class", "tooltip")
    .style("display", "none");
      
  tooltip.append("rect")
    .attr("width", 60)
    .attr("height", 20)
    .attr("fill", "red")
    .style("opacity", 0.5);

tooltip.append("g:text")
    .attr("x", 30)
    .attr("y", "1.2em")
    .style("text-anchor", "middle")
    .attr("font-size", "12px")
    .attr("font-weight", "bold");

</script>

https://d3js.org/d3.v4.min.js