Open-high-low-close chart

An example of a stock price or open-high-low-close chart. Red lines indicate the closing price is lower than the opening price - greens indicate the opposite. The grey line is a five day moving average of the closing price.

This is part of a series of visualisations called My Visual Vocabulary which aims to recreate every visualisation in the FT's Visual Vocabulary from scratch using D3.

<!DOCTYPE html>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<style>
  body {
    margin: 0;
  }
  
  .high-low, .open, .close {
    stroke-width: 2px;
  }
  
  .moving-average {
    fill: none;
    stroke: black;
    stroke-width: 2px;
    opacity: 0.5;
  }
</style>
<script>

var svg = d3.select("svg"),
    margin = {top: 75, right: 75, bottom: 75, left: 85},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");

// parse day, abbreviated month name, year without century
var parseTime = d3.timeParse("%d-%b-%y");

var tickSize = 3;
  
var x = d3.scaleTime()
    .rangeRound([0, width]);

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

x.domain([d3.min(data, function(d) { return d.Date; }),
           d3.max(data, function(d) { return d.Date; })]);
  
  y.domain([Math.floor(d3.min(data, function(d) { return d.Low; })),
           Math.ceil(d3.max(data, function(d) { return d.High; }))]);
  
  data = data.slice(0, data.length - 1);
  
  var ohlcs = g.append("g").attr("class", "ohlcs")
  	.selectAll("g")
  	.data(data)
  .enter().append("g")
  	.attr("class", "ohlc");
  
  ohlcs.append("path")
  	.attr("class", "high-low")
  	.attr("d", highLowGenerator)
  	.attr("stroke", colour);
  
  ohlcs.append("path")
  	.attr("class", "open")
  	.attr("d", openGenerator)
  	.attr("stroke", colour);
  
  ohlcs.append("path")
  	.attr("class", "close")
  	.attr("d", closeGenerator)
  	.attr("stroke", colour);
  
  var movingAverage = [];
  var days = 5;
  
  data.forEach(function(d, i) {
    var total = 0;
    var count = 0;
    for (var n = 0; n < days; n++) {
      if (data[i + n]) {
        total += data[i + n].Close;
        count++;
      }
    };

var average = total / count;
    var obj = {
      "Date": d.Date,
      "Average": average
    }
    movingAverage.push(obj);
  });
  
  
  var movingAverageLine = g.append("g")
  	.attr("class", "moving-average")
  	.append("path")
  	.datum(movingAverage)
  	.attr("d", movingAverageGenerator);
  
  var xAxis = g.append("g")
  	.attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
  	.style("font-family", "monospace")
    .call(d3.axisBottom(x));

var yAxis = g.append("g")
  		.attr("class", "y axis")
			.style("font-family", "monospace")
      .call(d3.axisLeft(y));
  
  g.append("text")
      .attr("fill", "#000")
      .attr("x", width / 2)
  		.attr("dy", -20)
      .attr("text-anchor", "middle")
  		.style("font-family", "monospace")
      .text("Stock Price ($)");
  
    // Add a small label for the symbol name.
  g.append("text")
      .attr("x", width - 30)
      .attr("y", height - 25)
      .style("text-anchor", "end")
  		.style("font-family", "monospace")
  		.style("font-size", "14")
      .text("NYSE: TWTR");
});

</script>

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