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javascript - 无需单击即可访问chartJs中特定条形的yLabel

问题描述

我正在研究应根据 yLabel 中的值确定条形背景颜色的 chartJs。

我们如何访问chartjs中特定条形的yLabel进行比较？

const waterFChart = new Chart(canvasRef.current, {
    plugins: [ChartDataLabels],
    type: "bar",
    data: {
        labels: ["Label 1", "Label 2", "Label 3", "Label 4", "Label 5"],
        datasets: [
            {
                label: 'Failures',
                type: "bar",
                data: [10, 20, 30, 41, 51],
                //background color is assigned based on if yLabel of bar matches testValue
                backgroundColor: ylabel === testvalue ? "red" : "yellow",
                //how can we access yLabelhere
            hoverBackgroundColor: darkBar,
            stack: 'Stack 1',
        }
}
);

标签： javascriptreactjschart.js

解决方案

您可以像这样使用可编写脚本的选项：

const yVal = 12;
const primeCrolor = "green";
const secondColor = "red"

const options = {
  type: 'bar',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
      label: '# of Votes',
      data: [12, 19, 3, 5, 2, 3],
      backgroundColor: (ctx) => {
        if (!ctx.parsed) {
          return secondColor
        }
        const allTicks = ctx.chart.scales.y.ticks.map(e => e.value);
        return (allTicks.includes(yVal) && ctx.parsed.y === yVal) ? primeCrolor : secondColor;
      }
    }]
  },
  options: {
    // Scale config only needed for example to force the correct labels
    scales: {
      y: {
        min: 0,
        max: 20,
        ticks: {
          stepSize: 2
        }
      }
    }
  }
}

const ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);
<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.5.1/chart.js"></script>
</body>

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