Chart.js v2: How to make tooltips always appear on line chart? - chart.js

Question

I have searched through for the solution but I have found solution to pie charts only. For example this one : Chart.js v2: How to make tooltips always appear on pie chart?
I just want make the tooltip visible without hovering. I have tried registering new pluginService but its not working and its producing this error
Uncaught TypeError: Cannot read property 'call' of undefined
this is what I have so far
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;
}
}
})
var myChart = new Chart(ctx, {
type: 'line',
data: {
labels: ["January", "February", "March", "April", "May", "June", "July"],
datasets: [{
label: "My First dataset",
fillColor: "rgba(220,220,220,0.2)",
strokeColor: "rgba(220,220,220,1)",
pointColor: "rgba(220,220,220,1)",
pointStrokeColor: "#fff",
pointHighlightFill: "#fff",
pointHighlightStroke: "rgba(220,220,220,1)",
data: [65, 59, 80, 81, 56, 55, 40]
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
},
showAllTooltips: true
}
});
appreciate any helps tq

Answer 1

When using the latest stable version of Chart.js (2.9.3), it works with the following changes.
Instead of Chart.pluginService.register, use Chart.plugin.register
Instead of change _options : chart.options write _options : chart.options.tooltips
Please have a look at your amended code below.
Chart.plugins.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.tooltips,
_active: [sector]
}, chart));
});
});
chart.options.tooltips.enabled = false; // turn off normal tooltips
}
},
afterDraw: function(chart, easing) {
if (chart.config.options.showAllTooltips) {
if (!chart.allTooltipsOnce) {
if (easing !== 1) {
return;
}
chart.allTooltipsOnce = true;
}
chart.options.tooltips.enabled = true;
Chart.helpers.each(chart.pluginTooltips, function(tooltip) {
tooltip.initialize();
tooltip.update();
tooltip.pivot();
tooltip.transition(easing).draw();
});
chart.options.tooltips.enabled = false;
}
}
});
new Chart("chart", {
type: 'line',
data: {
labels: ["January", "February", "March", "April", "May", "June", "July"],
datasets: [{
label: "My First dataset",
fillColor: "rgba(220,220,220,0.2)",
strokeColor: "rgba(220,220,220,1)",
pointColor: "rgba(220,220,220,1)",
pointStrokeColor: "#fff",
pointHighlightFill: "#fff",
pointHighlightStroke: "rgba(220,220,220,1)",
data: [65, 59, 80, 81, 56, 55, 40]
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
},
showAllTooltips: true
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.3/Chart.min.js"></script>
<canvas id="chart" height="100"></canvas>