[JavaScript] Draw a stacked graph with chart.js

What I want to do

Stacked graphs can be easily drawn by setting the 'stack:' option to the same value, but what I want to do is

• There are data a and b

• b is part of a

• I want to emphasize the ratio of b to a

Of course, I can draw a normal stacked graph of b and a-b, but if a-b is not that important, that is, since I want to focus on the ratio of b to a, I want to draw a bar graph with the bottoms of a and b aligned.

How to do it

Set beginAtZero: true

return new Chart(ctx, {
      type: 'bar',
      data: {
        labels: ["Graph"],
        datasets: [
          {
            label: "a",
            data: [a],
            backgroundColor: 'salmon',
          },        
          {
            label: "b",
            data: [b],
            backgroundColor: 'dodgerblue',
          },  
        ]
      },
      options: {
        scales: {
          x: {
            stacked: true,
          },
          y: {
            beginAtZero: true,
          },
        },
      },
    })

I can draw a graph like the one below