[Chartjs]-Chart js bar chart add animation to change color

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You can use setInterval() that repeatedly invokes code where you alternately change the color of a random bar or reset the colors. Also at the end of each cycle, you need to invoke chart.update().

let changeBarColor = true;
setInterval(() => {
  if (changeBarColor) {
    let i = randomInt(0, bgColors.length - 1);
    dataset.backgroundColor[i] = borderColors[i];
  } else {      
    dataset.backgroundColor = bgColors.slice(0);    
  }
  chart.update();
  changeBarColor = !changeBarColor;
}, 1000);

Please take a look at below code sample and see how it works in action.

const chart = new Chart(document.getElementById("chart"), {
  type: "bar",
  data: {
    labels: ["January", "February", "March", "April", "May", "June", "July"],
    datasets: [{
      label: "My Dataset",
      data: [65, 59, 80, 81, 56, 55, 40],
      backgroundColor: ["rgba(255, 99, 132, 0.2)", "rgba(255, 159, 64, 0.2)", "rgba(255, 205, 86, 0.2)", "rgba(75, 192, 192, 0.2)", "rgba(54, 162, 235, 0.2)", "rgba(153, 102, 255, 0.2)", "rgba(201, 203, 207, 0.2)"],
      borderColor: ["rgb(255, 99, 132)", "rgb(255, 159, 64)", "rgb(255, 205, 86)", "rgb(75, 192, 192)", "rgb(54, 162, 235)", "rgb(153, 102, 255)", "rgb(201, 203, 207)"],
      borderWidth: 1
    }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks: {
          beginAtZero: true
        }
      }]
    }
  }
});

function randomInt(min, max) {
    min = Math.ceil(min);
    max = Math.floor(max);
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

const dataset = chart.config.data.datasets[0];
const bgColors = dataset.backgroundColor.slice(0);
const borderColors = dataset.borderColor.slice(0);

let changeBarColor = true;
setInterval(() => {
  if (changeBarColor) {
    let i = randomInt(0, bgColors.length - 1);
    dataset.backgroundColor[i] = borderColors[i];
  } else {      
    dataset.backgroundColor = bgColors.slice(0);    
  }
  chart.update();
  changeBarColor = !changeBarColor;
}, 1000);
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.min.js"></script>
<canvas id="chart" height="80"></canvas>

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