如何在chart.js中使条形图对称？

// 创建canvas元素
var canvas = document.getElementById("myChart");

// 创建条形图的配置对象
var chartConfig = {
  type: 'bar',
  data: {
    labels: ['A', 'B', 'C', 'D'],
    datasets: [{
      label: 'Positive',
      data: [10, 20, 30, 40],
      backgroundColor: 'rgba(75, 192, 192, 0.2)',
      borderColor: 'rgba(75, 192, 192, 1)',
      borderWidth: 1
    }, {
      label: 'Negative',
      data: [-10, -20, -30, -40],
      backgroundColor: 'rgba(255, 99, 132, 0.2)',
      borderColor: 'rgba(255, 99, 132, 1)',
      borderWidth: 1
    }]
  },
  options: {
    scales: {
      y: {
        ticks: {
          min: -50,
          max: 50
        }
      }
    }
  }
};

// 创建条形图
var myChart = new Chart(canvas, chartConfig);