Bitcoin vs. Ether Price, July 2015 to Sept. 2017

Bitcoin data from Coindesk

Ether data from Etherscan

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    const svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500)

const parseBTCTime = d3.timeParse("%Y-%m-%d");
		const parseETHTime = d3.timeParse("%m/%d/%Y");

const x = d3.scaleTime()
        .rangeRound([0, width - 40]);

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

const BTCLine = d3.line()
        .x(d => x(d.Date))
        .y(d => y(d["Close Price"]));

const ETHLine = d3.line()
        .x(d => x(d["Date(UTC)"]))
        .y(d => y(d.Value));

d3.csv("coindesk-bpi-USD-close_data-2015-07-29_2017-09-23.csv", (d) => {
      d.Date = parseBTCTime(d.Date);
      d["Close Price"] = +d["Close Price"];
      return d;
    }, (error, data) => {
      if (error) throw error;

x.domain(d3.extent(data, d => d.Date));
      y.domain(d3.extent(data, d => d["Close Price"]));

g.append("g")
          .attr("transform", `translate(0,${height})`)
          .attr("fill", "dimgrey")
          .call(d3.axisBottom(x))
        .select(".domain")
          .remove();

g.append("g")
          .call(d3.axisLeft(y))
        .append("text")
          .attr("fill", "SteelBlue")
          .attr("transform", "rotate(-90)")
          .attr("y", 6)
          .attr("dy", "0.71em")
          .attr("text-anchor", "end")
          .text("BTC Price ($)");

g.append("path")
          .datum(data)
          .attr("fill", "none")
          .attr("stroke", "SteelBlue")
          .attr("stroke-linejoin", "round")
          .attr("stroke-linecap", "round")
          .attr("stroke-width", 1.5)
          .attr("d", BTCLine);
    });

d3.csv("export-EtherPrice.csv", (d) => {
      d["Date(UTC)"] = parseETHTime(d["Date(UTC)"]);
      d.Value = +d.Value;
      return d;
    }, (error, data) => {
      if (error) throw error;

x.domain(d3.extent(data, d => d["Date(UTC)"]));
      y.domain(d3.extent(data, d => d.Value));

g.append("g")
          .attr("transform", `translate(${width},0)`)
          .attr("fill", "dimgrey")
          .call(d3.axisLeft(y))
        .append("text")
          .attr("fill", "LightSalmon")
          .attr("transform", "rotate(-90)")
          .attr("y", 6)
          .attr("dy", "0.71em")
          .attr("text-anchor", "end")
          .text("ETH Price ($)");

g.append("path")
          .datum(data)
          .attr("fill", "none")
          .attr("stroke", "LightSalmon")
          .attr("stroke-linejoin", "round")
          .attr("stroke-linecap", "round")
          .attr("stroke-width", 1.5)
          .attr("d", ETHLine);
});

</script>
</body>

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