Stacked bar chart with tooltips

A simple stacked coloumn graph built using d3's stack layout.

The SVG tooltip is based on this gist by Mike Bostock. In short, the tooltip's group, comprised of a rect and a text element, are created when the chart is first drawn and set to be hidden. Action is applied to the stacks' rects: on mouseover the group become visible; on mousemove the mouse's XY position is captured and used to transform/translate the group.

If you ajust the tooltip's XY offset, keep in mind that there can be no overlap between the group and the mouse's position or the group's visibility will remain hidden.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <title>d3.js learning</title>
  <script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
  <style type="text/css">
  svg {
    font: 10px sans-serif;
    shape-rendering: crispEdges;
  }
  .axis path,
  .axis line {
    fill: none;
    stroke: #000;
  }
 
  path.domain {
    stroke: none;
  }
 
  .y .tick line {
    stroke: #ddd;
  }
  </style>

</head>
<body>
<script type="text/javascript">
// Setup svg using Bostock's margin convention
var margin = {top: 20, right: 160, bottom: 35, left: 30};
var width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;
var svg = d3.select("body")
  .append("svg")
  .attr("width", width + margin.left + margin.right)
  .attr("height", height + margin.top + margin.bottom)
  .append("g")
  .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
/* Data in strings like it would be if imported from a csv */
var data = [
  { year: "2012", "Other": "56", "Employee Commuting": "1867", "Business Air Travel": "3814", "Energy": "2832" },
  { year: "2013", "Other": "85", "Employee Commuting": "1729", "Business Air Travel": "3542", "Energy": "3010" },
  { year: "2014", "Other": "132", "Employee Commuting": "1481", "Business Air Travel": "3280", "Energy": "2734" },
  { year: "2015", "Other": "106", "Employee Commuting": "1326", "Business Air Travel": "2852", "Energy": "2583" },
  { year: "2016", "Other": "58" , "Employee Commuting": "1252", "Business Air Travel": "2891", "Energy": "2362" },
];  
  
var parse = d3.time.format("%Y").parse;
// Transpose the data into layers
var dataset = d3.layout.stack()(["Other", "Employee Commuting", "Business Air Travel", "Energy"].map(function(fruit) {
  return data.map(function(d) {
    return {x: parse(d.year), y: +d[fruit]};
  });
}));
// Set x, y and colors
var x = d3.scale.ordinal()
  .domain(dataset[0].map(function(d) { return d.x; }))
  .rangeRoundBands([10, width-10], 0.02);
var y = d3.scale.linear()
  .domain([0, d3.max(dataset, function(d) {  return d3.max(d, function(d) { return d.y0 + d.y; });  })])
  .range([height, 0]);
var colors = ["#7f7f7f", "#ed7d31", "#548235", "4472c4"];
// Define and draw axes
var yAxis = d3.svg.axis()
  .scale(y)
  .orient("left")
  .ticks(5)
  .tickSize(-width, 0, 0)
  .tickFormat(d3.format(","));
var xAxis = d3.svg.axis()
  .scale(x)
  .orient("bottom")
  .tickFormat(d3.time.format("%Y"));
svg.append("g")
  .attr("class", "y axis")
  .call(yAxis);
svg.append("g")
  .attr("class", "x axis")
  .attr("transform", "translate(0," + height + ")")
  .call(xAxis);
// Create groups for each series, rects for each segment 
var groups = svg.selectAll("g.cost")
  .data(dataset)
  .enter().append("g")
  .attr("class", "cost")
  .style("fill", function(d, i) { return colors[i]; });
var rect = groups.selectAll("rect")
  .data(function(d) { return d; })
  .enter()
  .append("rect")
  .attr("x", function(d) { return x(d.x); })
  .attr("y", function(d) { return y(d.y0 + d.y); })
  .attr("height", function(d) { return y(d.y0) - y(d.y0 + d.y); })
  .attr("width", x.rangeBand())
  .on("mouseover", function() { tooltip.style("display", null); })
  .on("mouseout", function() { tooltip.style("display", "none"); })
  .on("mousemove", function(d) {
    var xPosition = d3.mouse(this)[0] - 15;
    var yPosition = d3.mouse(this)[1] - 25;
    tooltip.attr("transform", "translate(" + xPosition + "," + yPosition + ")");
    tooltip.select("text").text(d.y).format(",");
  });
// Draw legend
var legend = svg.selectAll(".legend")
  .data(colors)
  .enter().append("g")
  .attr("class", "legend")
  .attr("transform", function(d, i) { return "translate(30," + i * 19 + ")"; });
 
legend.append("rect")
  .attr("x", width - 18)
  .attr("width", 18)
  .attr("height", 18)
  .style("fill", function(d, i) {return colors.slice().reverse()[i];});
 
legend.append("text")
  .attr("x", width + 5)
  .attr("y", 9)
  .attr("dy", ".35em")
  .style("text-anchor", "start")
  .text(function(d, i) { 
    switch (i) {
      case 3: return "Other";
      case 2: return "Employee Commuting";
      case 1: return "Business Air Travel";
      case 0: return "Energy";
    }
  });
// Prep the tooltip bits, initial display is hidden
var tooltip = svg.append("g")
  .attr("class", "tooltip")
  .style("display", "none");
    
tooltip.append("rect")
  .attr("width", 30)
  .attr("height", 20)
  .attr("fill", "white");
tooltip.append("text")
  .attr("x", 15)
  .attr("dy", "1.2em")
  .style("text-anchor", "middle")
  .attr("font-size", "12px")
  .attr("font-weight", "bold");
</script>
</body>
</html>

Modified http://d3js.org/d3.v3.min.js to a secure url

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