[Chartjs]-Chart.js v2: How to make tooltips always appear on pie chart?

With the new Chart.js 2.1 you can write a plugin to do this and control it via an options property

Preview

Script

Note that you need to register the plugin before you initialize the chart

Chart.pluginService.register({
    beforeRender: function (chart) {
        if (chart.config.options.showAllTooltips) {
            // create an array of tooltips
            // we can't use the chart tooltip because there is only one tooltip per chart
            chart.pluginTooltips = [];
            chart.config.data.datasets.forEach(function (dataset, i) {
                chart.getDatasetMeta(i).data.forEach(function (sector, j) {
                    chart.pluginTooltips.push(new Chart.Tooltip({
                        _chart: chart.chart,
                        _chartInstance: chart,
                        _data: chart.data,
                        _options: chart.options,
                        _active: [sector]
                    }, chart));
                });
            });

            // turn off normal tooltips
            chart.options.tooltips.enabled = false;
        }
    },
    afterDraw: function (chart, easing) {
        if (chart.config.options.showAllTooltips) {
            // we don't want the permanent tooltips to animate, so don't do anything till the animation runs atleast once
            if (!chart.allTooltipsOnce) {
                if (easing !== 1)
                    return;
                chart.allTooltipsOnce = true;
            }

            // turn on tooltips
            chart.options.tooltips.enabled = true;
            Chart.helpers.each(chart.pluginTooltips, function (tooltip) {
                tooltip.initialize();
                tooltip.update();
                // we don't actually need this since we are not animating tooltips
                tooltip.pivot();
                tooltip.transition(easing).draw();
            });
            chart.options.tooltips.enabled = false;
        }
    }
});

and then

new Chart(ctx, {
    type: 'pie',
    data: data,
    options: {
        showAllTooltips: true
        ...

With the older 2.x version, you should able to move the same (or similar, I’m not sure about the earlier data structure ) to the options.animation.onComplete

Fiddle – http://jsfiddle.net/q15ta78q/

I was looking for similar solution and came across this chartjs plugin Chart.PieceLabel.js. It has configs to display modes like label, value and percentage.

According to the closed issue on the github page for chart.js, displaying tool tips permanently is not recommended.

This comment closing this issue gives more detail:

https://github.com/chartjs/Chart.js/issues/1861#issuecomment-442852768

and this is the recommended plugin for permanent data labels:

https://github.com/chartjs/chartjs-plugin-datalabels

If you got here because you were looking for a way to make pie charts always look hovered like I was. here is the solution that helped me:
https://nobal.in/technology/chart-js/how-to-highlight-selected-in-pie-doughnut/

I just needed a way to programmatically enlarge one part of the pie chart, and this is exactly it