line shape

<!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;
    }
    svg {
      width: 100%;
      height: 100%;
    }
  </style>
</head>

<body>
  <svg></svg>
  <script>
    var city = 'Austin';
    var width = 834;
    var height = 300;
    var marginValue = 25;
    var margin = {
      top: marginValue,
      bottom: marginValue,
      left: marginValue,
      right: marginValue
    };
    
    // dataset of city temperatures across time
    d3.tsv('data.tsv', (err, data) => {
      // clean the data
      
      // data = data.slice(0, 200);
      
      data.forEach(d => {
        d.date = d3.timeParse("%Y%m%d")(d.date);
        d.date = new Date(d.date); // x
        d[city] = ++d[city]; // y
      });
      
      // scales
      var xExtent = d3.extent(data, d => d.date);
      
      // min && max dates
      var xScale = d3.scaleTime()
      	.domain(xExtent)
      	.range([margin.left, width - margin.right]);

var yMax = d3.max(data, d => d[city]);
      var yScale = d3.scaleLinear()
      	.domain([0, yMax])
      	.range([height - margin.bottom, margin.top]);
      
      var line = d3.line()
      	.x((d) => {return xScale(d.date);})
      	.y((d) => {return yScale(d[city])})
      	.curve(d3.curveCatmullRom)
      
      d3.select('svg')
      	.append('path')
      	.attr('d', line(data))
      	.attr('fill', 'none')
	      .attr('stroke', 'tomato');
      
    });
  </script>
</body>

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