line2

<!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 = "San Francisco";
    var width = 800;
    var height = 300;
    var margin = {top:20,bottom:20,left:20,right:20};
   
    d3.tsv ('data.tsv',(err,data) => {
      data.forEach(d => {
        d.date = d3.timeParse('%Y%m%d')(d.date);
        d.date = new Date(d.date);
        d[city] = ++d[city];//converting data to integer
      });
      
      //create the scales
      var xExtent = d3.extent(data,d => d.date);
      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]);

//create the line
      var line = d3.line()
      	.x(function(d) {return xScale(d.date)})
      	.y (function(d) {return yScale(d[city])})
      	.curve(d3.curveStep);
      
      var svg = d3.select('svg');
      
      svg.append('path')
      	.attr('d',line(data))
      	.attr('fill','none')
      	.attr('stroke','#00f')
      
      var xAxis = d3.axisBottom()
      	.scale(xScale);
      var yAxis = d3.axisLeft()
      	.scale(yScale);
      
      svg.append('g')
      	.attr('transform','translate('+[0,height-margin.bottom]+')')
      	.call(xAxis);
      
      svg.append('g')
      	.attr('transform','translate('+[margin.left,0]+')')
				.call(yAxis);
      
      
    });
  </script>
</body>

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