Fetch data for Chart.js tooltips dynamically

Question

Fetch data for Chart.js tooltips dynamically

One common way to load information for a tooltip in a chart is by using the following code snippet:

window.myLine = new Chart(chart, {
  type: 'line',
  data: lineChartData,
  options: {
    tooltips: {
      enabled: true,
      mode: 'single',
      callbacks: {
        label: function(tooltipItems, data) {
          return tooltipItems.yLabel + ' €';
        }
      }
    },
  }
});

However, I faced an issue where I needed to retrieve values asynchronously by calling a function and show a loading spinner until the response is ready. How can I achieve this dynamic behavior?

javascript chart.js bar-chart

Answer 1

Answer №1

To update chart.js asynchronously, consider using the update() method. You can also implement recursion if the label needs to change based on the data point hovered by the user.

window.myLine = new Chart(chart, {
  type: 'line',
  data: lineChartData,
  options: {
    tooltips: {
      enabled: true,
      mode: 'single',
      callbacks: {
        label: asyncTooltipLabel
      }
    },
  }
});

function asyncTooltipLabel(tooltipItems, data) {
  // Perform some asynchronous operation
  setTimeout(function() {
    // Handle asynchronous result
    const result = (tooltipItems[0].index * 2) + ' €';

    const newTooltipConfig = {
       enabled: true,
       mode: 'single',
       callbacks: {
           label: function(newTooltipItems, newData) {
              if (newTooltipItems[0].index === tooltipItems[0].index && newTooltipItems[0].datasetIndex === tooltipItems[0].datasetIndex) return result;
              else asyncTooltipLabel(newTooltipItems, newData);
           }
       }
    }

    // Update tooltip configuration
    window.myLine.options.tooltips = newTooltipConfig;
    window.myLine.update();
  }, 2000);
}

Answer 2

To update chart.js asynchronously, consider using the update() method. You can also implement recursion if the label needs to change based on the data point hovered by the user.

window.myLine = new Chart(chart, {
  type: 'line',
  data: lineChartData,
  options: {
    tooltips: {
      enabled: true,
      mode: 'single',
      callbacks: {
        label: asyncTooltipLabel
      }
    },
  }
});

function asyncTooltipLabel(tooltipItems, data) {
  // Perform some asynchronous operation
  setTimeout(function() {
    // Handle asynchronous result
    const result = (tooltipItems[0].index * 2) + ' €';

    const newTooltipConfig = {
       enabled: true,
       mode: 'single',
       callbacks: {
           label: function(newTooltipItems, newData) {
              if (newTooltipItems[0].index === tooltipItems[0].index && newTooltipItems[0].datasetIndex === tooltipItems[0].datasetIndex) return result;
              else asyncTooltipLabel(newTooltipItems, newData);
           }
       }
    }

    // Update tooltip configuration
    window.myLine.options.tooltips = newTooltipConfig;
    window.myLine.update();
  }, 2000);
}

Fetch data for Chart.js tooltips dynamically

Answer №1

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