D3 Examples - Test 2,000 dots in browser for sanity

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<!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; }
    body { padding: 2em;}
    body { background-color: #F8F7F1;}
  </style>
</head>
​
<body>
  <script>
    const config = {
      width: 600,
      height: 400
    };
    const svg = d3.select("body").append("svg")
      .attr("width", config.width)
      .attr("height", config.height)
​
    const x = d3.scaleTime()
        .range([0, config.width]);
    const y = d3.scaleLinear()
        .range([config.height, 0]);
    const xExtent = [new Date('2015-12-31'), new Date()];
    const yExtent = d3.extent([0,50]);
    x.domain(xExtent);
    y.domain(yExtent);
    
        d3.json('polls.json', function(err, data) {
      
      const parseDate = d3.timeParse('%Y-%m-%d');
      data.forEach((d, i) =>
        d.date = parseDate(d.date)
      );
      data.forEach(function(d, i, o) {
        if (d.poll != 'NA') {
          d.date = new Date(d.date);
          d.poll = +d.poll;
        } else {
          o.splice(i, 1);
        }
      });
      
            svg.selectAll('circle')
        .data(data).enter()
        .append('circle')
        .attr('cx', d => x(d.date))
        .attr('cy', d => y(d.poll))
        .attr('r', 4)
        .style('opacity', .2)
    })
​
  </script>
</body>
​
    