- y-axis group
- bars group
- x-axis group
virtual el 1 virtual el 2
Enter Selection
const rects = d3.selectAll('rect').data(data)
rects.enter().append('rect').attr()
Scales
linear scale
3000----------------500 3000----------------500px 1500----------------250px 0-------------------0
Domain[0,3000]---------Range[0,500]
[names]--------------band scale------------------x cord bandwidth(width of each different bar on the chart)