Develop Reference

Chart JS custom message on tooltip, not x and y axis

I am displaying a bar chart that has 3 different pieces of information, (project name, number of days remaining, and the end date.) I am displaying the project name on one axis, and the number of days remaining determines the height of the bar. Currently, when I hover over a bar the tooltip displays the information already on the x and y axis. I want it to instead have the end date.
ie: project "b" will end in 2 days (August 4th), when I hover over the bar I want the tooltip to say "End date of 2022-08-04" instead of "b Work Days Remaining: 2"
My json of the data looks like this:
[{"po_num": "a", "days_rem": 10, "date_end": "2022-08-16"},
{"po_num": "b", "days_rem": 2, "date_end": "2022-08-04"},
{"po_num": "c", "days_rem": 6, "date_end": "2022-08-10"}]
Here is the link of the current graph.
https://i.stack.imgur.com/HefRz.png
Here is an MS paint rendering of what I am trying to do:
https://i.stack.imgur.com/GAT2I.png
The implementation code:
link = "{{{BASE_BACK_URL}}}";
$.getJSON(link, function (data) {
let po_names = [];
let days_rem = [];
for (let i = 0; i < data.length; i++) {
po_names.push(data[i]["po_num"]);
days_rem.push(data[i]["days_rem"]);
}
const ctx = document.getElementById('po-timeline-chart');
const myChart = new Chart(ctx, {
type: 'horizontalBar',
data: {
labels: po_names,
datasets: [{
label: 'Work Days Remaining',
data: days_rem,
backgroundColor: 'rgb(0, 89, 178)'
}],
},
options: {
legend: {
align: "end"
},
scales: {
xAxes: [{
ticks: {
beginAtZero: true
}
}]
}
}
});
});

Solution listed below:
$.getJSON(link, function (data) {
let po_names = [];
let days_rem = [];
for (let i = 0; i < data.length; i++) {
po_names.push(data[i]["po_num"]);
days_rem.push(data[i]["days_rem"]);
}
const ctx = document.getElementById("po-timeline-chart");
const myChart = new Chart(ctx, {
type: "horizontalBar",
data: {
labels: po_names,
datasets: [
{
label: "Work Days Remaining",
data: days_rem,
backgroundColor: "rgb(0, 89, 178)",
},
],
},
options: {
tooltips: {
enabled: true,
callbacks: {
// To change title in tooltip
title: (data) => {
return "This PO will run out on";
},
// To change label in tooltip
label: (data) => {
return date_end[data['index']];
},
},
},
legend: {
align: "end",
},
scales: {
xAxes: [
{
ticks: {
beginAtZero: true,
},
},
],
},
},
});
});

Live Update Callback -> afterTitle with Array via JSON file

I'm working on a chart, I'm live updating the Chart every 5 seconds that the data comes in. I could manage to get the info from the database and update it really easy, but I just came across a problem with involves setting a path to a part of the chart, in the case: options->tootltips->callbacks->afterTitle and inside of it create an array and pass the array from the JSON to an array inside the callback.
What I would need to do, In a really brief way is, since I already made a function to update the info from my Data and Labels, somehow I will need to make inside this function, a path to the afterTitle, than I will be able send the fifth array, in with stores the data. As you can see in my function, I could manage to do it for the data and label.
I can't have another function that updates, so basically I can't have 2 loadData(), because it makes the Chart blink every time it updates, and that's not what I'm aiming for (The chart can't blink).
Inside this patch, I made an example that didn't work, with is the //:
$.getJSON('loadchart.php', function(response) {
myLineChart.data.datasets[0].data = response[0];
myLineChart.data.datasets[1].data = response[1];
myLineChart.data.datasets[2].data = response[2];
myLineChart.data.datasets[3].data = response[3];
myLineChart.data.labels = response[4];
//The response array that I need is response[5];
//myLineChart.options.tooltips.callbacks[1] = return response[tooltipItem[0]['index']];
myLineChart.update();
});
All my Chart so you can see the path:
<script>
function loadData() {
$.getJSON('loadchart.php', function(response) {
myLineChart.data.datasets[0].data = response[0];
myLineChart.data.datasets[1].data = response[1];
myLineChart.data.datasets[2].data = response[2];
myLineChart.data.datasets[3].data = response[3];
myLineChart.data.labels = response[4];
myLineChart.update();
});
}
loadData();
setInterval(loadData, 5000);
var lbl = [];
var ctx1 = document.getElementById('mychart1').getContext('2d');
var myLineChart = new Chart(ctx1, {
type: 'line',
data: {
labels: lbl,
datasets: [
{
label: "Corrente 1",
data: [],
borderWidht: 6,
borderColor: 'red',
backgroundColor: 'transparent'
},
{
label: "Corrente 2",
data: [],
borderWidht: 6,
borderColor: 'blue',
backgroundColor: 'transparent'
},
{
label: "Corrente 3",
data: [],
borderWidht: 6,
borderColor: 'green',
backgroundColor: 'transparent'
},
{
label: "Corrente Total",
data: [],
borderWidht: 6,
borderColor: 'black',
backgroundColor: 'transparent'
},
]
},
options: {
animation:{
update: 0
},
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}],
xAxes: [{
gridLines: {
display: false
}
}]
},
title: {
display: true,
fontSize: 20,
text: "Gráfico das Correntes"
},
labels: {
fontStyle: "bold",
},
layout: {
padding: {
left: 0,
right: 0,
top: 0,
bottom: 0
}
},
tooltips: {
enabled: true,
mode: 'single',
responsive: true,
backgroundColor: 'black',
titleFontFamily: "'Arial'",
titleFontSize: 14,
titleFontStyle: 'bold',
titleAlign: 'center',
titleSpacing: 4,
titleMarginBottom: 10,
bodyFontFamily: "'Mukta'",
bodyFontSize: 14,
borderWidth: 2,
borderColor: 'grey',
callbacks:{
title: function(tooltipItem, data) {
return data.labels[tooltipItem[0].index];
},
afterTitle: function(tooltipItem, data) {
var tempo = [];
return tempo[tooltipItem[0]['index']];
},
label: function(tooltipItem, data) {
var label = data.datasets[tooltipItem.datasetIndex].label || '';
if (label) {
label += ': ';
}
label += (tooltipItem.yLabel)+"A";
return label;
}
}
},
aspectRatio: 1,
maintainAspectRatio: false
}
});
</script>
The part I need is this one:
afterTitle: function(tooltipItem, data) {
var tempo = [];
return tempo[tooltipItem[0]['index']];

This will display a clock but you can also set it to 5000 seconds and call your chart update. Which i would suggest to put in some kind of AJAX to let it work asynchonous.
<!DOCTYPE html>
<html>
<head>
<script>
function startTime() {
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
m = checkTime(m);
s = checkTime(s);
document.getElementById('txt').innerHTML =
h + ":" + m + ":" + s;
var t = setTimeout(startTime, 500); //<---- !!!
}
function checkTime(i) {
if (i < 10) {i = "0" + i}; // add zero in front of numbers < 10
return i;
}
</script>
</head>
<body onload="startTime()">
<div id="txt"></div>
</body>
</html>

As you mention in afterTitle function you want to create an array and pass the array from the JSON to an array inside the callback, and the missing part is you are creating an array tempo and treating it like an object tempo[tooltipItem[0]['index']];, but what you need to do is push this object tooltipItem[0]['index'] to tempo array.
Please replace afterTitle function with the below code
afterTitle: function(tooltipItem, data) {
var tempo = [];
return tempo.push(tooltipItem[0]['index']);

Display multiple tags in the legend for a single data value in Chart.js

I have graph that I built with the Chart.js library :
Normally, Sshare is represented with two color, red and green. In the legend, however, Sshare displays with just the first color value, red.
How can I get both Sshare colors to show in the legend?
I tried searching for a solution in the Chart.js documentation, but could not find a way to edit the legend properties.
My code:
<script>
// chart colors //BLUE & RED & VERT
var colors = ['#007bff','#dc3545',"#008000"];
var colors_suggested =[];
var labels_in =[];
var mshare_value =[];
var svalues =[];
var data_work_in =[
{ "ID":12, "Les": "AB", "Name": " AB_12", "Mmin": 75, "Sshare": 29},
{ "ID":13, "Les": "BB", "Name": " BB_13", "Mmin": 26.8, "Sshare": 36}
];
for (var i = 0; i < data_work_in.length;i++)
{
labels_in.push(data_work_in[i].Name+";"+data_work_in[i].Mill);
mshare_value.push(data_work_in[i].Mmin);
svalues.push(data_work_in[i].Sshare);
if ( data_work_in[i].Sshare >= data_work_in[i].Mmin)
colors_suggested.push(colors[2]);
else {
colors_suggested.push(colors[1]);
}
}
var chBar = document.getElementById("chBar");
var chartData = {
// Label of Entity
labels: labels_in,
// Value of percent category RTI|| VSM ...
datasets: [{
label: 'Mmin',
data: mshare_value,
backgroundColor: colors[0]
},
{
label: 'Sshare',
data: svalues,
xAxisID:'xAxis1',
backgroundColor: colors_suggested
}]
};
if (chBar) {
// new graph
new Chart(chBar, {
type: 'bar',
data: chartData,
options: {
scales: {
xAxes:[
{
barPercentage: 0.9,
categoryPercentage: 0.7,
id:'xAxis1',
type:"category",
ticks:{
callback:function(label){
var sublabel_x = label.split(";")[0];
var label_p = label.split(";")[1];
return sublabel_x;
}
}
},
{
id:'xAxis2',
type:"category",
gridLines: {
drawOnChartArea: false, // only want the grid lines for one axis to show up
},
ticks:{
callback:function(label){
var sublabel_x = label.split(";")[0];
var label_p = label.split(";")[1];
return label_p;
}
}
}],
yAxes: [{
ticks: {
beginAtZero: false
},
scaleLabel: {
display: true,
labelString: '%'
}
}]
},
legend: {
display: true,
legendText : ['Mmin','Sshare']
}
}
});
}
</script>

Horizontal stacked angular bar charts

I am trying to implement an Angular horizontal stacked bar chart- Something like this example.
However, I want just one bar that is stacked.
I am working with AngularJS and Chart.js. I have the example showing on the page.
In the PieController, ChartData contains:
{"data":["63","38"],"labels":["Ford","GM"]}
In the example, instead of the label on the outside, I would like the label and then the number to be inside the chart. Like [=====Ford 63====|===GM 38===] the equals represent bar colors. There will be more data points than the current two.
Here is my page
<div ng-controller="PieController">
data {{ChartData}} //testing purposes
<div ng-init="getBarChart()">
<canvas id="Chart1"></canvas>
</div>
Here is my JavaScript controller
app.controller('PieController', function($scope, ChartService) {
$scope.getBarChart = function(){
ChartService.get({name: 'main'}, function(data) {
$scope.ChartData = data;
var barOptions_stacked = {
tooltips: {
enabled: false
},
hover: {
animationDuration: 0
},
scales: {
xAxes: [{
ticks: {
beginAtZero: true,
fontFamily: "'Open Sans Bold', sans-serif",
fontSize: 11
},
scaleLabel: {
display: false
},
gridLines: {},
stacked: true
}],
yAxes: [{
gridLines: {
display: false,
color: "#fff",
zeroLineColor: "#fff",
zeroLineWidth: 0
},
ticks: {
fontFamily: "'Open Sans Bold', sans-serif",
fontSize: 11
},
stacked: true
}]
},
legend: {
display: false
},
animation: {
onComplete: function () {
var chartInstance = this.chart;
var ctx = chartInstance.ctx;
ctx.textAlign = "left";
ctx.font = "9px Open Sans";
ctx.fillStyle = "#fff";
Chart.helpers.each(this.data.datasets.forEach(function (dataset, i) {
var meta = chartInstance.controller.getDatasetMeta(i);
Chart.helpers.each(meta.data.forEach(function (bar, index) {
data = dataset.data[index];
if (i == 0) {
ctx.fillText(data, 50, bar._model.y + 4);
} else {
ctx.fillText(data, bar._model.x - 25, bar._model.y + 4);
}
}), this)
}), this);
}
},
pointLabelFontFamily: "Quadon Extra Bold",
scaleFontFamily: "Quadon Extra Bold",
};
var ctx = document.getElementById("Chart1");
var myChart = new Chart(ctx, {
type: 'horizontalBar',
data: {
labels: ["2014", "2013", "2012", "2011"],
datasets: [{
data: [727, 589, 537, 543, 574],
backgroundColor: "rgba(63,103,126,1)",
hoverBackgroundColor: "rgba(50,90,100,1)"
}, {
data: [238, 553, 746, 884, 903],
backgroundColor: "rgba(163,103,126,1)",
hoverBackgroundColor: "rgba(140,85,100,1)"
}, {
data: [1238, 553, 746, 884, 903],
backgroundColor: "rgba(63,203,226,1)",
hoverBackgroundColor: "rgba(46,185,235,1)"
}]
},
options: barOptions_stacked,
})
});//end chat service.get
}
});
Instead of hard coding in the dataset which is what its doing now, is there a way I can use the data "ChartData" that I outlined in the beginning of the post?
I'm not sure how to do it or if its even possible.

In order to get the label to show in the bar, reference the labels property of $scope.ChartData:
ctx.fillText($scope.ChartData.labels[index] +" "+ data, 50, bar._model.y + 4);
Instead of hard coding in the dataset which is what its doing now, is there a way I can use the data "ChartData" that I outlined in the beginning of the post?
Use properties from the data variable (supplied by the ChartService get function) i.e. data.labels and data.data instead of the hard-coded values.
So update the labels line from:
labels: ["2014", "2013", "2012", "2011"],
To this:
labels: data.labels,
And similarly for the datasets:
datasets: [{
data: data.data,
So when creating the Chart it should look like this:
var myChart = new Chart(ctx, {
type: 'horizontalBar',
data: {
labels: data.labels,
datasets: [{
data: data.data,
backgroundColor: "rgba(63,103,126,1)",
hoverBackgroundColor: "rgba(50,90,100,1)"
}]
},
options: barOptions_stacked,
});
Expand the code snippet below for a demonstration.
Note: there is currently an issue with the resize-listener, blocked by a CORS issue - I am trying to find a way to disable that.
Update:
Per your comment about stacking the bars (horizontally) - yes that is possible. Just have one element in the datasets array for each item. One simple way to have this is to use Array.map() to create an array similar to the example:
var bgColors = [
"rgba(63,103,126,1)",
"rgba(50,90,100,1)"
];
var hoverBgColors = [
"rgba(50,90,100,1)",
"rgba(140,85,100,1)"
];
var datasets = data.data.map(function(value, index) {
return {
data: [value],
backgroundColor: bgColors[index],
hoverBackgroundColor: hoverBgColors[index]
}
});
Then use variable datasets when creating the Chart object:
var myChart = new Chart(ctx, {
type: 'horizontalBar',
data: {
labels: data.labels,
datasets: datasets
},
options: barOptions_stacked,
});
Also, there is some weird math going on for the location of the second label but the helper function can be updated like below (I tried dividing the x value by 75 but that may need to be adjusted - I am not sure what "appropriate" values are for that ...):
if (i == 0) {
ctx.fillText($scope.ChartData.labels[i] + " " + data, 50, bar._model.y + 4);
} else {
ctx.fillText($scope.ChartData.labels[i] + " " + data, (bar._model.x - 25) / 75, bar._model.y + 4);
}
var app = angular.module('myApp', []);
app.factory('ChartService', function() {
return { //dummy chart service
get: function(obj, callback) {
var data = {
"data": ["63", "38"],
"labels": ["Ford", "GM"]
};
callback(data);
}
};
});
app.controller('PieController', function($scope, ChartService) {
$scope.getBarChart = function() {
ChartService.get({
name: 'main'
}, function(data) {
$scope.ChartData = data;
var barOptions_stacked = {
tooltips: {
enabled: false
},
hover: {
animationDuration: 0
},
scales: {
xAxes: [{
ticks: {
beginAtZero: true,
fontFamily: "'Open Sans Bold', sans-serif",
fontSize: 11
},
scaleLabel: {
display: false
},
gridLines: {},
stacked: true
}],
yAxes: [{
gridLines: {
display: false,
color: "#fff",
zeroLineColor: "#fff",
zeroLineWidth: 0
},
ticks: {
fontFamily: "'Open Sans Bold', sans-serif",
fontSize: 11
},
stacked: true
}]
},
legend: {
display: false
},
animation: {
onComplete: function() {
var chartInstance = this.chart;
var ctx = chartInstance.ctx;
ctx.textAlign = "left";
ctx.font = "9px Open Sans";
ctx.fillStyle = "#fff";
Chart.helpers.each(this.data.datasets.forEach(function(dataset, i) {
var meta = chartInstance.controller.getDatasetMeta(i);
Chart.helpers.each(meta.data.forEach(function(bar, index) {
data = dataset.data[index];
if (i == 0) {
ctx.fillText($scope.ChartData.labels[i] + " " + data, 50, bar._model.y + 4);
} else {
ctx.fillText($scope.ChartData.labels[i] + " " + data, (bar._model.x - 25) / 75, bar._model.y + 4);
}
}), this)
}), this);
}
},
pointLabelFontFamily: "Quadon Extra Bold",
scaleFontFamily: "Quadon Extra Bold",
};
var ctx = document.getElementById("Chart1");
var bgColors = [
"rgba(63,103,126,1)",
"rgba(50,90,100,1)"
];
var hoverBgColors = [
"rgba(50,90,100,1)",
"rgba(140,85,100,1)"
];
var datasets = data.data.map(function(value, index) {
return {
data: [value],
backgroundColor: bgColors[index],
hoverBackgroundColor: hoverBgColors[index]
}
});
var myChart = new Chart(ctx, {
type: 'horizontalBar',
data: {
//use empty labels because the labels are on the bars
labels: data.labels.map(function() {
return '';
}),
datasets: datasets
},
options: barOptions_stacked,
})
}); //end chat service.get
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.1.3/Chart.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="myApp" ng-controller="PieController">
data {{ChartData}} //testing purposes
<div ng-init="getBarChart()">
<canvas id="Chart1"></canvas>

ChartJS New Lines '\n' in X axis Labels or Displaying More Information Around Chart or Tooltip with ChartJS V2

I'm using chart.js (V2) to try to build a bar chart that has more information available to user without having to hover over or click anywhere. I've provided two examples of how I hope to edit my chart.
Two edited versions of what I hope to achieve
As can be seen, I hope to place (somewhere), some extra information outside of the labels. I had hope that by adding '\n' to the labels I might have been able to get what I was looking for similar to option A.
Some edited code is provided blow:
var barChartData = {
labels: playerNames,
datasets: [{
label: 'Actual Score/Hour',
backgroundColor: "rgba(0, 128, 0,0.5)",
data: playerScores
}, {
label: 'Expected Score/Hour',
backgroundColor: "rgba(255,0,0,0.5)",
data: playerExpected
}]
};
function open_win(linktosite) {
window.open(linktosite)
}
canvas.onclick = function(evt){
var activePoints = myBar.getElementsAtEvent(evt);
console.log(activePoints);
linktosite = 'https://www.mytestsite.com/' + activePoints[1]['_model']['label'];
open_win(linktosite);
};
window.onload = function() {
var ctx = document.getElementById("canvas").getContext("2d");
window.myBar = new Chart(ctx, {
type: 'bar',
data: barChartData,
options: {
title:{
display:true,
text:"Player Expected and Actual Score per Hour"
},
tooltips: {
mode: 'label'
},
responsive: true,
scales: {
xAxes: [{
stacked: false,
}],
yAxes: [{
stacked: false
}]
},
animation: {
onComplete: function () {
var ctx = this.chart.ctx;
ctx.textAlign = "center";
Chart.helpers.each(this.data.datasets.forEach(function (dataset) {
Chart.helpers.each(dataset.metaData.forEach(function (bar, index) {
// console.log("printing bar" + bar);
ctx.fillText(dataset.data[index], bar._model.x, bar._model.y - 10);
}),this)
}),this);
}
}
}
});
// Chart.helpers.each(myBar.getDatasetMeta(0).data, function(rectangle, index) {
// rectangle.draw = function() {
// myBar.chart.ctx.setLineDash([5, 5]);
// Chart.elements.Rectangle.prototype.draw.apply(this, arguments);
// }
// }, null);
};
At this point I'd be satisfied with having the extradata anywhere on the bar. Any help would be appreciated. Thanks~

Chart.js v2.1.5 allows for multi-line labels using nested arrays (v2.5.0 fixes it for radar graphs):
...
data: {
labels: [["Jake", "Active: 2 hrs", "Score: 1", "Expected: 127", "Attempts: 4"],
["Matt", "Active: 2 hrs", "Score: 4", "Expected: 36", "Attempts: 4"]],
...
However, this does mean that you will have to pre-calculate the label values.

var config = {
type: 'line',
data: {
labels: [["January","First Month","Jellyfish","30 of them"], ["February","Second Month","Foxes","20 of them"], ["March","Third Month","Mosquitoes","None of them"], "April", "May", "June", "July"],
datasets: [{
label: "My First dataset",
data: [65, 40, 80, 81, 56, 85, 45],
backgroundColor: "rgba(255,99,132,0.2)",
}, {
label: "My Second dataset",
data: [40, 80, 21, 56, 85, 45, 65],
backgroundColor: "rgba(99,255,132,0.2)",
}]
},
scales : {
xAxes : [{
gridLines : {
display : false,
lineWidth: 1,
zeroLineWidth: 1,
zeroLineColor: '#666666',
drawTicks: false
},
ticks: {
display:true,
stepSize: 0,
min: 0,
autoSkip: false,
fontSize: 11,
padding: 12
}
}],
yAxes: [{
ticks: {
padding: 5
},
gridLines : {
display : true,
lineWidth: 1,
zeroLineWidth: 2,
zeroLineColor: '#666666'
}
}]
},
spanGaps: true,
responsive: true,
maintainAspectRatio: true
};
var ctx = document.getElementById("myChart").getContext("2d");
new Chart(ctx, config);
<div class="myChart">
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.bundle.js"></script>
<canvas id="myChart"></canvas>
</div>
If a label is an array as opposed to a string i.e. [["June","2015"], "July"] then each element is treated as a separate line. The appropriate calculations are made to determine the correct height and width, and rotation is still supported.
charJS version 2.7.2 used
this also works in https://github.com/jtblin/angular-chart.js

If you are using Chart.js v2.7.1, the above solution might not work.
The solution that actually worked for us was adding a small plugin right in the data and options level:
const config = {
type: 'bar',
data: {
// ...
},
options: {
// ...
},
plugins: [{
beforeInit: function (chart) {
chart.data.labels.forEach(function (label, index, labelsArr) {
if (/\n/.test(label)) {
labelsArr[index] = label.split(/\n/)
}
})
}
}]
};
A full description of how to fix this issue can be found here.

With Chart.js v2.1, you can write a chart plugin to do this
Preview
Script
Chart.pluginService.register({
beforeInit: function (chart) {
var hasWrappedTicks = chart.config.data.labels.some(function (label) {
return label.indexOf('\n') !== -1;
});
if (hasWrappedTicks) {
// figure out how many lines we need - use fontsize as the height of one line
var tickFontSize = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].ticks.fontSize, Chart.defaults.global.defaultFontSize);
var maxLines = chart.config.data.labels.reduce(function (maxLines, label) {
return Math.max(maxLines, label.split('\n').length);
}, 0);
var height = (tickFontSize + 2) * maxLines + (chart.options.scales.xAxes[0].ticks.padding || 0);
// insert a dummy box at the bottom - to reserve space for the labels
Chart.layoutService.addBox(chart, {
draw: Chart.helpers.noop,
isHorizontal: function () {
return true;
},
update: function () {
return {
height: this.height
};
},
height: height,
options: {
position: 'bottom',
fullWidth: 1,
}
});
// turn off x axis ticks since we are managing it ourselves
chart.options = Chart.helpers.configMerge(chart.options, {
scales: {
xAxes: [{
ticks: {
display: false,
// set the fontSize to 0 so that extra labels are not forced on the right side
fontSize: 0
}
}]
}
});
chart.hasWrappedTicks = {
tickFontSize: tickFontSize
};
}
},
afterDraw: function (chart) {
if (chart.hasWrappedTicks) {
// draw the labels and we are done!
chart.chart.ctx.save();
var tickFontSize = chart.hasWrappedTicks.tickFontSize;
var tickFontStyle = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].ticks.fontStyle, Chart.defaults.global.defaultFontStyle);
var tickFontFamily = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].ticks.fontFamily, Chart.defaults.global.defaultFontFamily);
var tickLabelFont = Chart.helpers.fontString(tickFontSize, tickFontStyle, tickFontFamily);
chart.chart.ctx.font = tickLabelFont;
chart.chart.ctx.textAlign = 'center';
var tickFontColor = Chart.helpers.getValueOrDefault(chart.options.scales.xAxes[0].fontColor, Chart.defaults.global.defaultFontColor);
chart.chart.ctx.fillStyle = tickFontColor;
var meta = chart.getDatasetMeta(0);
var xScale = chart.scales[meta.xAxisID];
var yScale = chart.scales[meta.yAxisID];
chart.config.data.labels.forEach(function (label, i) {
label.split('\n').forEach(function (line, j) {
chart.chart.ctx.fillText(line, xScale.getPixelForTick(i + 0.5), (chart.options.scales.xAxes[0].ticks.padding || 0) + yScale.getPixelForValue(yScale.min) +
// move j lines down
j * (chart.hasWrappedTicks.tickFontSize + 2));
});
});
chart.chart.ctx.restore();
}
}
});
and then
...
data: {
labels: ["January\nFirst Month\nJellyfish\n30 of them", "February\nSecond Month\nFoxes\n20 of them", "March\nThird Month\nMosquitoes\nNone of them", "April", "May", "June", "July"],
...
Note - we assume that the maximum content of one line will fit between the ticks (i.e. that no rotation logic is needed. I'm sure it's possible to incorporate rotation logic too, but it would be a tad more complicated)
You should format the tooltips to not show the x axis label, or format it to show a shorter version of the label.
Fiddle - http://jsfiddle.net/m0q03wpy/