Change Chart.js tooltip caret position

Question

I created a doughnut chart using Chart.js 2.5. The issue I’m having is with the tooltip. When I hover over the chart, a tooltip is displayed with a caret that always stays in the left or right side, like this:

I want to change the caret position so that it always show in the bottom. Is that possible?

Here is my chart code

var myChart = new Chart(ctx, {
    type: 'doughnut',
    data: {
        labels: ['Jan', 'Feb', 'Mar'],
        datasets: [{
            label: 'dataset',
            data: [30, 50, 20],
            backgroundColor: [
            'rgb(153, 102, 255)',
            'rgb(255, 205, 86)',
            'rgb(54, 162, 235)'
            ],
        }],
    }
})

Wilow

Answer 1

You could set yAlign property to bottom for tooltips in your chart options to display tooltip's caret always at the bottom position ...

options: {
    tooltips: {
        yAlign: 'bottom'
    }
}

ᴅᴇᴍᴏ

var ctx = document.getElementById("chart").getContext("2d");
var myChart = new Chart(ctx, {
    type: 'doughnut',
    data: {
        labels: ['Jan', 'Feb', 'Mar'],
        datasets: [{
            label: 'dataset',
            data: [30, 50, 20],
            backgroundColor: ['rgb(153, 102, 255)', 'rgb(255, 205, 86)', 'rgb(54, 162, 235)']
        }]
    },
    options: {
        responsive: false,
        tooltips: {
            yAlign: 'bottom'
        }
    }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js"></script>
<canvas id="chart" height="180"></canvas>

Shantay

Tooltip option doesn't seem to have yAlign property any longer or am I wrong? – Futures

@DongBinKim Still possible with // @ts-ignore – Cottonade

@DongBinKim it's reversed, as it applies to the caret and not the tooltip (weird API choice) – Portie

Answer 2

You can do this by setting the yAlign tooltips configuration option to "bottom":

options: {
    tooltips: {
      yAlign: "bottom"
    }
}

JSFiddle Demo: https://jsfiddle.net/tksr7bn9/

Raynor

Thanks for your response. Had to accept the other one since it was first :) – Wilow

@CamielJacobs I'm okay with that. Glad I could help. I wrote up this answer at the same time, and only saw the other answer after I posted it. Once you get enough reputation, you can just upvote all helpful answers. – Raynor

Answer 3

For anyone struggling to get this working in 2021+, the tooltip alignment option applies to the caret's position. So if you set the yAlign to 'bottom', that means that the tooltip has to be aligned at the top (in order for the caret to remain at the bottom). So it's simply backwards - if you need the tooltip to render at the bottom, set the caret's yAlign: 'top' instead.

Example:

var ctx = document.getElementById("chart").getContext("2d");
var myChart = new Chart(ctx, {
    type: 'doughnut',
    data: {
        labels: ['Jan', 'Feb', 'Mar'],
        datasets: [{
            label: 'dataset',
            data: [30, 50, 20],
            backgroundColor: ['rgb(153, 102, 255)', 'rgb(255, 205, 86)', 'rgb(54, 162, 235)']
        }]
    },
    options: {
        responsive: false,
        tooltips: {
            yAlign: 'top'
        }
    }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js"></script>
<canvas id="chart" height="180"></canvas>

Portie

Answer 4

Lot of ways to customize the tooltip. Here's a good example via CodePen.

https://codepen.io/mab213/pen/PZOXdE

customTooltips: function(tooltip) {
  // Tooltip Element
  var tooltipEl = $('#chartjs-tooltip');
  // Hide if no tooltip
  if (!tooltip) {
    tooltipEl.css({
      opacity: 1
    });
    return;
  }
  // Set caret Position
  tooltipEl.removeClass('above below');
  tooltipEl.addClass(tooltip.yAlign);
  tooltipEl.addClass(tooltip.xAlign);
  // Set Text
  tooltipEl.html(tooltip.text);
  // Find Y Location on page
  var top;
  if (tooltip.yAlign == 'above') {
    top = tooltip.y - tooltip.caretHeight - tooltip.caretPadding;
  } else {
    top = tooltip.y + tooltip.caretHeight + tooltip.caretPadding;
  }
  // Display, position, and set styles for font
  tooltipEl.css({
    opacity: 1,
    left: tooltip.chart.canvas.offsetLeft + tooltip.x + 'px',
    top: tooltip.chart.canvas.offsetTop + top + 'px',
    fontFamily: tooltip.fontFamily,
    fontSize: tooltip.fontSize,
    fontStyle: tooltip.fontStyle,
    xOffset: tooltip.xOffset,
  });
}

Bengaline