time_series

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v3.min.js"></script>
    <style>
      body {
        font-family: futura;
      }
			
      .axis {
        font-family: arial;
        font-size: 0.7em;
      }
      
			.axis text {
        font-size: 0.75em;
        stroke: none;
        font-family: 'Gill Sans', 'Gill Sans MT', Calibri, sans-serif;
    	}
      
      text {
        fill: black;
      }

path {
        fill: none;
        stroke: black;
        stroke-width: 1px;
      }

.tick {
        fill: none;
        stroke: black;
      }

rect {
        fill: #4eb0bb;
      }

#tooltip {
        position: absolute;
        width: 90px;
        height: auto;
        padding: 5px;
        margin-bottom: 10px;
        background-color: white;
        -webkit-box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.4);
        -moz-box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.4);
        box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.4);
        pointer-events: none;
      }

#tooltip.hidden {
        display: none;
      }

#tooltip p {
        margin: 0;
        font-family: sans-serif;
        font-size: 16px;
        line-height: 20px;
      }
    </style>

function draw(data) {
          "use strict";
        
        	// add a null data element so the axis extends past the last
          // bar of the histogram.
        	data.push({ count: 0, index: 1381});
          
          // set margins according to Mike Bostock's margin conventions
          // https://bl.ocks.org/mbostock/3019563
          var margin = {top: 25, right: 40, bottom: 50, left: 75};

// set height and width of chart
          var width = 960 - margin.left - margin.right,
              height = 500 - margin.top - margin.bottom;

// specify column we want to plot
          var field = 'count';
        	var mouse_field = 'extra';

// append the SVG tag with height and width to accommodate for margins
          var svg = d3.select("body")
                      .append("svg")
                          .attr("width", width + margin.left + margin.right)
                          .attr("height", height + margin.top + margin.bottom)
                      .append('g')
                          .attr('class','chart')
                          .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

// Append the title for the graph
          svg.append('text')
             .attr('x', width / 2)
             .attr('y', 0)
             .style('text-anchor', 'right')
             .text("Michael's First Chart Ever")

// bind our data to svg circles for the scatter plot
          svg.selectAll("rect")
              .data(data)
              .enter()
              .append("rect")

// maximum count
            var max_y = d3.max(data, function(d) {
                return +d[field];
            });

// get min/max price
            var price_extent = d3.extent(data, function(d){
                return +d['index'];
            });

// Create x-axis scale mapping dates -> pixels
            var price_scale = d3.scale.linear()
                .range([0, width])
                .domain(price_extent);

// Create y-axis scale mapping price -> pixels
            var measure_scale = d3.scale.linear()
                .range([height, 0])
                .domain([0, max_y]);

// Create D3 axis object from time_scale for the x-axis
            var price_axis = d3.svg.axis()
                .scale(price_scale)
                .tickFormat(d3.format('$'));

// Create D3 axis object from measure_scale for the y-axis
            var measure_axis = d3.svg.axis()
                .scale(measure_scale)
                .orient("left");

// Append SVG to page corresponding to the D3 x-axis
            var xaxis = svg.append('g')
                .attr('class', 'x axis')
                .attr('transform', "translate(0," + height + ")")
                .call(price_axis);

// Append SVG to page corresponding to the D3 y-axis
            svg.append('g')
                .attr('class', 'y axis')
                .call(measure_axis);

// add label to y-axis
            d3.select(".y.axis")
                .append("text")
                .attr('class', 'label')
                .text("Count")
                .attr("transform", "rotate(-90)")
                .attr("x", -(height / 2)).attr('y', -40)
                .style("text-anchor", "middle")
                .style("font-size", "1.5em");

bars.on("mousemove", function(d) {
              // get current positions
              var pos = d3.mouse(this);
              var tool = d3.select("#tooltip");
              var format = d3.format('$.2f');

//move the tooltip into position
              var xpos = pos[0] + margin.left - parseFloat(tool.style('width')) / 2;

var ypos = pos[1] + margin.top - parseFloat(tool.style('height')) - 15;

// move tooltip div
              tool.style("left", xpos + "px")
                .style("top", ypos + "px");

// set price display
              // tool.select("#key")
              //   .text(format(d['index']));

//set count value display
              tool.select("#value")
                .text(d['extra']);

// show the tooltip
              d3.select("#tooltip").classed("hidden", false);
            })
            .on("mouseout", function() {
              // hide tooltip
              d3.select("#tooltip").classed("hidden", true);
            });
        };
      </script>
  </head>
  <body>
    <script type="text/javascript">
    // load our data file asynchronously and pass the data
    // to the draw function once it is loaded.
    d3.json("data.json", draw);
    </script>

<div id="tooltip" class='hidden'>
        
        <p style="margin-top: 5px"><strong>Count: </strong><span id="value"></span></p>
    </div>
  </body>
</html>

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

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