d3-scales.js

let xScale = d3.scaleLinear()
  .domain([0, 3000])   // my x-variable has a max of 3000
  .range([0, 600]);   // my x-axis is 600px wide

let yScale = d3.scaleLinear()
  .domain([0, 1000])   // my y-variable has a max of 1000
  .range([400, 0]);   // my y-axis is 400px high
                      // (the max and min are reversed because the 
                      // SVG y-value is measured from the top)