HW9Json

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
  background-color: #F1F3F3    
}
.axis {
	font: 10px sans-serif;
}
.axis path,
.axis line {
  fill: none;
  stroke: #D4D8DA;
  stroke-width: 2px;
  shape-rendering: crispEdges;
}
.line {
  fill: none;
  stroke: #6F257F;
  stroke-width: 5px;
}
.overlay {
  fill: none;
  pointer-events: all;
}
.focus circle {
  fill: #F1F3F3;
  stroke: #6F257F;
  stroke-width: 5px;
}
  
.hover-line {
  stroke: #6F257F;
  stroke-width: 2px;
  stroke-dasharray: 3,3;
}
  
.focus-text {
	font: 10px sans-serif;  
  }
</style>
<body>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

//append svg object to the page
var svg = d3.select("svg"),
    margin = {top: 80, right: 80, bottom: 60, left: 80},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom;
  
var parseTime = d3.timeParse("%Y")
    bisectDate = d3.bisector(function(d) { return d.year; }).left;
  
var x = d3.scaleTime().range([0, width]);
var y = d3.scaleLinear().range([height, 0]);

g.append("g")
        .attr("transform", "translate(0," + height + ")")
        .call(d3.axisBottom(x));
    g.append("text")
    	.attr("y", -40 )
    	.attr("class", "axis axis--x")
      .attr("transform",
            "translate(" + (width/2) + " ," + 
                           (height + margin.top) + ")")
      .style("text-anchor", "middle")
    	.attr("fill", "#5D6971")
      .text("Year");
  
    g.append("g")
        .attr("class", "axis axis--y")
        .call(d3.axisLeft(y).ticks(6).tickFormat(function(d) { return d}))
      .append("text")
        .attr("transform", "rotate(-90)")
        .attr("y", 20 - margin.left)
    		.attr("x", 0 - (height / 2))
        .attr("dy", "1em")
        .style("text-anchor", "middle")
        .attr("fill", "#5D6971")
        .text("Total Number of Shootings");
    g.append("path")
        .datum(data)
        .attr("class", "line")
        .attr("d", line);
    var focus = g.append("g")
        .attr("class", "focus")
        .style("display", "none");
    focus.append("line")
        .attr("class", "x-hover-line hover-line")
        .attr("y1", 0)
        .attr("y2", height);
    focus.append("line")
        .attr("class", "y-hover-line hover-line")
        .attr("x1", width)
        .attr("x2", width);
    focus.append("circle")
        .attr("r", 7.5);
    focus.append("text")
        .attr("x", -80)
    		.attr ("y", -50)
    		.attr("class", "focus-text")
      	.attr("dy", ".31em");
    svg.append("rect")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
        .attr("class", "overlay")
        .attr("width", width)
        .attr("height", height)
        .on("mouseover", function() { focus.style("display", null); })
        .on("mouseout", function() { focus.style("display", "none"); })
        .on("mousemove", mousemove);
    function mousemove() {
      var x0 = x.invert(d3.mouse(this)[0]),
          i = bisectDate(data, x0, 1),
          d0 = data[i - 1],
          d1 = data[i],
          d = x0 - d0.year > d1.year - x0 ? d1 : d0;
      focus.attr("transform", "translate(" + x(d.year) + "," + y(d.total) + ")");
      focus.select("text").text(function() { return	"Total: " + d.total + ", Fatal Percentage: " + d.fatalpercentage + "%"; });
      focus.select(".x-hover-line").attr("y2", height - y(d.total));
      focus.select(".y-hover-line").attr("x2", width + width);
    }
});
</script>

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