Chartjs-ChartJS: Custom tooltip always displaying

The custom tooltip option is used for when you want to create/style your own tooltip using HTLM/CSS outside of the scope of the canvas (and not use the built in tooltips at all).

In order to do this, you must define a place outside of your canvas to contain your tooltip (e.g. a div) and then use that container within your tooltips.custom function.

Here is an example where I used a custom tooltip to display the hovered pie chart section percentage in the middle of the chart. In this example I’m generating my tooltip inside a div with id “chartjs-tooltip”. Notice how I interact with this div in my tooltips.custom function to position and change the value.

Also, the correct way to check if the tooltip should be hidden is to check it’s opacity. The tooltip object will always exist, but when it should not be visible, the opacity is set to 0.

Chart.defaults.global.tooltips.custom = function(tooltip) {
  // Tooltip Element
  var tooltipEl = document.getElementById('chartjs-tooltip');

  // Hide if no tooltip
  if (tooltip.opacity === 0) {
    tooltipEl.style.opacity = 0;
    return;
  }

  // Set Text
  if (tooltip.body) {
    var total = 0;

    // get the value of the datapoint
    var value = this._data.datasets[tooltip.dataPoints[0].datasetIndex].data[tooltip.dataPoints[0].index].toLocaleString();

    // calculate value of all datapoints
  this._data.datasets[tooltip.dataPoints[0].datasetIndex].data.forEach(function(e) {
      total += e;
    });

    // calculate percentage and set tooltip value
    tooltipEl.innerHTML = '<h1>' + (value / total * 100) + '%</h1>';
  }

  // calculate position of tooltip
  var centerX = (this._chartInstance.chartArea.left + this._chartInstance.chartArea.right) / 2;
  var centerY = ((this._chartInstance.chartArea.top + this._chartInstance.chartArea.bottom) / 2);

  // Display, position, and set styles for font
  tooltipEl.style.opacity = 1;
  tooltipEl.style.left = centerX + 'px';
  tooltipEl.style.top = centerY + 'px';
  tooltipEl.style.fontFamily = tooltip._fontFamily;
  tooltipEl.style.fontSize = tooltip.fontSize;
  tooltipEl.style.fontStyle = tooltip._fontStyle;
  tooltipEl.style.padding = tooltip.yPadding + 'px ' + tooltip.xPadding + 'px';
};

Here is the full codepen example.

I hope that helps clear things up!