[Chartjs]-How to highlight a section of a stack in all bars in a stacked barchart in chartjs

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0👍

✅

With reference to @LeeLenalee’s solution, I’ve come up with the answer for the React implementation

options: {
  onHover: (e, activeEls) => {
    if (activeEls.length === 0) {
      this.chart.chartInstance.config.data.datasets.forEach((dataset) => {
        dataset.backgroundColor =
          dataset.backgroundColor.length === 9
            ? dataset.backgroundColor.slice(0, -2)
            : dataset.backgroundColor;
      });
      this.chart.chartInstance.update();
      return;
    }

    const hoveredEl = this.chart.chartInstance.getDatasetAtEvent(e)[0];

    this.chart.chartInstance.config.data.datasets.forEach((dataset, i) => {
      const [boldColor, lightColor] =
        dataset.backgroundColor.length === 9
          ? [dataset.backgroundColor.slice(0, -2), dataset.backgroundColor]
          : [dataset.backgroundColor, dataset.backgroundColor + "4D"];
      dataset.backgroundColor =
        hoveredEl._datasetIndex === i ? boldColor : lightColor;
    });

    this.chart.chartInstance.update();
  }
}

where this.chart is the ref to my <Bar /> component.

Notice that I have

const [boldColor, lightColor] =
  dataset.backgroundColor.length === 9
    ? [dataset.backgroundColor.slice(0, -2), dataset.backgroundColor]
    : [dataset.backgroundColor, dataset.backgroundColor + "4D"];
  dataset.backgroundColor =
    hoveredEl._datasetIndex === i ? boldColor : lightColor;

from line-17 to line-20. This helps to avoid the unnecessary glitch that I saw in @LeeLenalee’s code snippet when the bar’s opacity was changing.

1👍

You can use the onHover callback for it.

Live example:

var options = {
  type: 'bar',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
        label: '# of Votes',
        data: [12, 19, 3, 5, 2, 3],
        backgroundColor: '#FF0000',
      },
      {
        label: '# of Points',
        data: [7, 11, 5, 8, 3, 7],
        backgroundColor: '#0000FF'
      }
    ]
  },
  options: {
    onHover: (e, activeEls, chart) => {
      if (activeEls.length === 0) {
        chart.data.datasets.forEach((dataset) => {
          dataset.backgroundColor = dataset.backgroundColor.length === 9 ? dataset.backgroundColor.slice(0, -2) : dataset.backgroundColor;
        });
        chart.update();
        return;
      }

      const hoveredEl = chart.getElementsAtEventForMode(e, 'point', {
        intersect: true
      }, true)[0]

      chart.data.datasets.forEach((dataset, i) => {
        dataset.backgroundColor = (hoveredEl.datasetIndex === i || dataset.backgroundColor.length === 9) ? dataset.backgroundColor : dataset.backgroundColor + '4D';
      });

      chart.update();
    },
    scales: {
      y: {
        stacked: true
      },
      x: {
        stacked: true
      }
    }
  }
}

var 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/3.4.0/chart.js"></script>
</body>

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