Scales

<!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%;
      background-color: gold;
    }
  </style>
</head>

<body>
  <svg></svg>
  <script>
    const city = 'San Francisco'
    const width = 900
    const height = 400

// dataset of city temperatures across time
    d3.tsv('data.tsv', (err, data) => {
      // clean the data
      data.forEach(d => {
        d.date = new Date(d.date) // x
        ++d[city] // y
      })

// get min/max
      const min = d3.min(data, d => d[city])
      const max = d3.max(data, d => d[city])

console.log(min, max)
      // or use extent, which gives back [min, max]
      const extent = d3.extent(data, d => d[city])
      console.log(extent)

// try different scales, change the ranges, see what happens
      const yScale = d3
        .scaleLinear()
        .domain(extent)
        .range([height, 0])

// try passing in tick valuess
      const yAxis = d3.axisLeft().scale(yScale)
      const xAxis = d3.axisLeft().scale(yScale)

d3
      .select('svg')
      .append('g')
      .attr('transform', 'translate(40, 20)')
      .call(xAxis)
    })
</script>
</body>

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