Simple Area Chart D3 V4

<html>
  <head>
  </head>
  <body>
    <script src="https://code.jquery.com/jquery-latest.min.js"></script>
    <script src="https://d3js.org/d3.v4.min.js"></script>
    <div id="chart" width="800" height="500" style="width: 800;height: 500">
      <svg width="800" height="450" class="chartSvg"></svg>
      <a
        href="https://stackoverflow.com/users/7430694/chandrakant-thakkar"
        style="position: absolute;top: 87%;left: 77%;"
        target="_blank"
      >
        <img
          src="https://stackoverflow.com/users/flair/7430694.png"
          width="208"
          height="58"
          alt="profile for Chandrakant Thakkar at Stack Overflow, Q&amp;A for professional and enthusiast programmers"
          title="profile for Chandrakant Thakkar at Stack Overflow, Q&amp;A for professional and enthusiast programmers"
        />
      </a>
    </div>
    <script>
      var groupChartData = [
        // { "Team A": 0, "Team B": 0, over: 0 },
        { "Team A": 8, "Team B": 15, over: 1 },
        { "Team A": 15, "Team B": 17, over: 2 },
        { "Team A": 19, "Team B": 22, over: 3 },
        { "Team A": 38, "Team B": 30, over: 4 },
        { "Team A": 41, "Team B": 37, over: 5 },
        { "Team A": 47, "Team B": 38, over: 6 },
        { "Team A": 54, "Team B": 44, over: 7 },
        { "Team A": 67, "Team B": 46, over: 8 },
        { "Team A": 68, "Team B": 54, over: 9 },
        { "Team A": 76, "Team B": 63, over: 10 },
        { "Team A": 80, "Team B": 71, over: 11 },
        { "Team A": 80, "Team B": 91, over: 12 },
        { "Team A": 88, "Team B": 94, over: 13 },
        { "Team A": 93, "Team B": 103, over: 14 },
        { "Team A": 100, "Team B": 108, over: 15 },
        { "Team A": 109, "Team B": 122, over: 16 },
        { "Team A": 126, "Team B": 137, over: 17 },
        { "Team A": 147, "Team B": 147, over: 18 },
        { "Team A": 157, "Team B": 150, over: 19 },
        { "Team A": null, "Team B": 155, over: 20 }
      ];

var columnsInfo = { "Team A": "Team A", "Team B": "Team B" };

const yAxisG = mainG
        .append("g")
        .classed("yAxisG", true)
        .attr("transform", `translate(${margin.left},${margin.top})`);

//CBT:draw y Axis start
      yAxisG
        .call(d3.axisLeft(yAxisScale))
        .append("text")
        .attr("transform", "rotate(-90)")
        .attr("y", -margin.left * 0.5)
        .attr("x", -(height - (margin.top + margin.bottom)) / 2)
        .style("fill", "#C4C4C4")
        .style("font-weight", "bold")
        .style("font-size", "14px")
        .text("Runs");
      //CBT:draw y Axis end

var line = d3
        .line()
        .x(function(d) {
          return xAxisScale(d.x);
        })
        .y(function(d) {
          return yAxisScale(d.y);
        });

// define the area
var area = d3.area()
    .x(function(d) { return xAxisScale(d.x); })
    .y0(height-(margin.bottom+margin.top))
    .y1(function(d) { return yAxisScale(d.y); });

//CBT:Draw first line start
      const group1Line = mainG
        .append("g")
        .attr("transform", `translate(${margin.left},${margin.top})`)
        .append("g")
        .classed("group1-line", true);
      group1Line
        .append("path")
        .data([
          groupChartData
            .filter(function(d, i) {
              //CBT:remove last blank or value is 0 data to show only that much of line
              if (
                (d[group1Field] != null && d[group1Field] != undefined) ||
                i == 0
              )
                return d;
            })
            .map(d => {
              return { x: d[xAxisField], y: d[group1Field] };
            })
        ])
        .attr("d",line)
        .style("stroke", function(d) {
          return "#2a98cd";
        })
        .style("fill", "none")
        .style("stroke-width", "3px");

group1Line
        .append("path")
        .data([
          groupChartData
            .filter(function(d, i) {
              //CBT:remove last blank or value is 0 data to show only that much of line
              if (
                (d[group1Field] != null && d[group1Field] != undefined) ||
                i == 0
              )
                return d;
            })
            .map(d => {
              return { x: d[xAxisField], y: d[group1Field] };
            })
        ])
        .attr("d",area)
        .style("fill-opacity", "0.3")
        .style("fill", "#2a98cd");

//CBT:Draw first line end

//CBT:Draw second line start
      const group2Line = mainG
        .append("g")
        .attr("transform", `translate(${margin.left},${margin.top})`)
        .append("g")

.classed("group2-line", true);
      group2Line
        .append("path")
        .data([
          groupChartData
            .filter(function(d, i) {
              //CBT:remove last blank or value is 0 data to show only that much of line
              if ((d[group2Field] != null && d[group2Field] != undefined) || i == 0)
                return d;
            })
            .map(d => {
              return { x: d[xAxisField], y: d[group2Field] };
            })
        ])
        .attr("d", line)
        .style("stroke", function(d) {
          return "#df7247";
        })
        .style("fill", "none")
        .style("stroke-width", "3px");

group2Line
        .append("path")
        .data([
          groupChartData
            .filter(function(d, i) {
              //CBT:remove last blank or value is 0 data to show only that much of line
              if ((d[group2Field] != null && d[group2Field] != undefined) || i == 0)
                return d;
            })
            .map(d => {
              return { x: d[xAxisField], y: d[group2Field] };
            })
        ])
        .attr("d", area)
        .style("fill", "#df7247")
        .style("fill-opacity", "0.3");

//CBT:Draw second line end
      const circleRadius = 4;
      const tooltip = mainG
        .append("g")
        .attr("transform", `translate(${margin.left},${margin.top})`);
      var mouseOverG = mainG
        .append("g")
        .attr("class", "mouseOverEffect")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
      const moveOnMouseOverG = mouseOverG
        .append("g")
        .attr("transform", "translate(0,0)");
      const groupLine = moveOnMouseOverG
        .append("path")
        .attr("d", `M0 0 L0 ${height - (margin.bottom + margin.top)} Z`)
        .attr("class", "mouse-line")
        .style("stroke", "black")
        .style("stroke-opacity", "0")
        .style("stroke-width", "2px");

const group1Circle = moveOnMouseOverG
        .append("circle")
        .attr("r", circleRadius)
        .style("fill", "transparent")
        .style("stroke", "green")
        .style("stroke-width", "2px")
        .style("stroke-opacity", "0");

const group2Circle = moveOnMouseOverG
        .append("circle")
        .attr("r", circleRadius)
        .style("fill", "transparent")
        .style("stroke", "green")
        .style("stroke-width", "2px")
        .style("stroke-opacity", "0");

//CBT:tooltip start
     
      var tooltipG = tooltip
        .append("g")
        .attr("font-family", "sans-serif")
        .attr("font-size", 10)
        .attr("style", "opacity:0")
        .attr("transform", `translate(0,0)`);

const rectTooltip = tooltipG.append("rect").style("fill", "#ccc");

const textTooltip = tooltipG.append("text").text("");

//CBT:tooltip end

mouseOverG
        .append("svg:rect")
        .data([groupChartData])
        .attr("width", width - (margin.left + margin.right))
        .attr("height", height - (margin.top + margin.bottom))
        .attr("fill", "none")
        .attr("pointer-events", "all")
        .on("mouseenter", function(data) {
          group1Circle.style("stroke-opacity", 1);
          group2Circle.style("stroke-opacity", 1);
          groupLine.style("stroke-opacity", 1);
          tooltipG.style("opacity", 1);
        })
        .on("mouseout", function(data) {
          group1Circle.style("stroke-opacity", 0);
          group2Circle.style("stroke-opacity", 0);
          groupLine.style("stroke-opacity", 0);
          tooltipG.style("opacity", 0);
        })
        .on("mousemove", function(data) {
          var mouse = d3.mouse(this);
          console.log(
            "X",
            mouse[0],
            "xValue:",
            Math.round(xAxisScale.invert(mouse[0]))
          );
          moveOnMouseOverG.attr(
            "transform",
            `translate(${xAxisScale(
              Math.round(xAxisScale.invert(mouse[0]))
            )},0)`
          );

let tooltipXPosition =
            xAxisScale(Math.round(xAxisScale.invert(mouse[0]))) + 10;

const filteredData = data.filter(
            d => d[xAxisField] == Math.round(xAxisScale.invert(mouse[0]))
          );
          textTooltip.text("Over:" + filteredData[0][xAxisField]);
          const heightOfText = textTooltip.node().getBBox().height;
          const widthOfText = textTooltip.node().getBBox().width;
          textTooltip.text("");
          textTooltip
            .append("tspan")
            .attr("y", heightOfText + 10)
            .attr("x", 10)
            .text("Over: " + filteredData[0][xAxisField]);

textTooltip
            .append("tspan")
            .attr("y", heightOfText * 2 + 15)
            .attr("x", 10)
            .text(group1Field + ": " + filteredData[0][group1Field]);

textTooltip
            .append("tspan")
            .attr("y", heightOfText * 3 + 20)
            .attr("x", 10)
            .text(group2Field + ": " + filteredData[0][group2Field]);
          rectTooltip.attr("height", textTooltip.node().getBBox().height + 20);
          rectTooltip.attr("width", textTooltip.node().getBBox().width + 20);
          if (
            textTooltip.node().getBBox().width + 20 + tooltipXPosition >
            width - (margin.left + margin.right)
          ) {
            tooltipXPosition =
              tooltipXPosition - 20 - (textTooltip.node().getBBox().width + 20);
          }
          tooltipG.attr("transform", `translate(${tooltipXPosition},10)`);

if (filteredData.length > 0 && filteredData[0][group1Field] != null) {
            group1Circle.style("stroke-opacity", 1);
            group1Circle.style("cy", yAxisScale(filteredData[0][group1Field]));
          } else {
            group1Circle.style("stroke-opacity", 0);
          }
          if (filteredData.length > 0 && filteredData[0][group2Field] != null) {
            group2Circle.style("stroke-opacity", 1);
            group2Circle.style("cy", yAxisScale(filteredData[0][group2Field]));
          } else {
            group2Circle.style("stroke-opacity", 0);
          }
        });

//CBT:Legend Start
      $("#chart").before(
        "<div id='Legend_chart' class='pmd-card-body' style='margin-top:0; margin-bottom:0;'></div>"
      );
      var keys = [
        {
          color: "#2a98cd",
          label: group1Field
        },
        {
          color: "#df7247",
          label: group2Field
        }
      ];
      keys.forEach(function(d) {
        var cloloCode = d.color;
        $("#Legend_chart").append(
          "<span class='team-graph team1' style='display: inline-block; margin-right:10px;'>\
  			<span style='background:" +
            cloloCode +
            ";width: 10px;height: 10px;display: inline-block;vertical-align: middle;'>&nbsp;</span>\
  			<span style='padding-top: 0;font-family:Source Sans Pro, sans-serif;font-size: 13px;display: inline;'>" +
            d.label +
            " </span>\
  		</span>"
        );
      });
      //CBT:Legend End
    </script>
  </body>
</html>

Modified http://code.jquery.com/jquery-latest.min.js to a secure url

https://code.jquery.com/jquery-latest.min.js

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