Develop Reference

Chart.js Tooltip Trigger Issue

In my implementation of Chart.js (v3.9.1) I have a line graph with tooltips. The tooltip plugin definition is as follows ( ... added for brevity in code):
this.graph = new Chart(document.querySelector('#m-graph'), {
type: 'line',
data: {...},
options: {
responsive: true,
maintainAspectRatio: false,
interaction: {
mode: 'point'
},
stacked: false,
showTooltips: true,
title: {
display: false
},
scales: scales,
plugins: {
legend: {...},
tooltip: {
position: 'nearest',
callbacks: {
label: (context) => {
...
}
}
}
}
}
});
When I hover over data points, the more "to the right" I go on the X axis, the further away from each data point I need to hover to get the tooltip to popup. GIF below shows issue.
Any ideas/advice on what settings to toggle to fix this? Or is this a bug?

Thank you to #Konrad Linkowski above for pushing me into the right direction. I had the canvas element for the graph sized with width: calc(100% - 5rem). Removing that fixes the issue.

Chartjs-plugin-zoom plugin does not change x axis labels

I am working with the chart.js module in order to plot some data and am using the chartjs-plugin-zoom in order to enable zooming and panning however although the zooming works the labels on the x axis will not change for whatever reason.
I have seen similar questions but they all dealt with time series data and therefore the advice was unhelpful.
Here is the plot zoomed out:
and here is it zoomed in:
The key thing to notice is how the labels on the y axis have changed but the x axis labels have not changed. Here is the relevant config variable of the chart:
const config3 = {
type: 'line',
data: {
labels: [I ran out of chars but this is just a very long list of numbers in this format: 1,2,3,4,5],
datasets: [
{
label: "",
backgroundColor: '#'+Math.floor(Math.random()*16777215).toString(16),
borderColor: '#0071BC',
data: [I ran out of chars but this is just a very long list of numbers in this format: 1,2,3,4,5],
fill: false,
borderWidth: 1,
},
],
},
options: {
responsive: true,
title: {
display: true,
text: 'Peak: -1.2188'
},
tooltips: {
mode: 'index',
intersect: false,
},
hover: {
mode: 'nearest',
intersect: true
},
scales: {
xAxes: [{
display: true,
scaleLabel: {
display: true,
labelString: 'Frequency (Hz)'
},
ticks:{
autoSkip: true,
maxTicksLimit: 20
},
}],
yAxes: [{
display: true,
scaleLabel: {
display: true,
labelString: 'Amplitude'
}
}],
},
plugins:{
zoom: {
pan: {
enabled: true,
mode: 'xy',
speed: 20,
threshold: 10,
},
zoom: {
enabled: true,
drag: false,
mode: "xy",
speed: 0.1,
// sensitivity: 0.1,
}
}
},
elements: {
point:{
radius: 0
}
}
}
};
If needed I can provide more code but I imagine the mistake is probably contained in the config. I tried changing zoom.mode to be 'x' but that did not work.

In case someone else comes along this I figured out a solution that is pretty unintuitive.
The first problem is the way that labels are dealt with in chart.js and because they are treated as categories not x data the way that I thought they were. Therfore first you must pass your data in as coordinates in this format:
(as shown in this documentation: https://www.chartjs.org/docs/latest/charts/line.html)
data: [{
x: 10,
y: 20
}, {
x: 15,
y: 10
}]
And delete the labels variable.
However this will not work with line charts despite what the documentation says. To get around this you can set: type: 'scatter' and inside the dataset write showLine: true
This will generate a line plot where the x labels are auto generated and zooming will work perfectly.
I also think there was a performance boost which is a nice bonus.

ChartJS - How to increase the maximum degree of label rotation on x-axis?

I have a line chart, and at first, all the labels on x-axis are fully horizontal. Something like this:
Now if add more data, the labels start to rotate:
Until comes a point where it seems to have reached the maximum degree to which it can rotate:
By the looks of it, I think the maximum degree is 45. So now, if I add a little more data, instead of rotating the labels more, it removes every one in two labels, and becomes like this:
How can I increase this degree to 90, so that the labels rotate as much as becoming fully vertical?
Here's the code I used for the chart:
new Chart(chart, {
type: 'line',
data: chart_data,
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: false
}
}]
},
legend: {
position: 'top',
labels: {
boxWidth: 5,
usePointStyle: true
}
},
events: ['click', 'mousemove'],
onClick: clicked,
pan: {
enabled: true,
mode: 'x',
onPanComplete: function(event) {
console.log(event)
}
},
zoom: {
enabled: true,
mode: 'x'
}
}
});

You can configure this using the maxRotation property of the common tick configuration object.
Your code needs to be modified like so:
options: {
scales: {
xAxes: [{
ticks: {
maxRotation: 90
}
}],
yAxes: [{
...

The keyword of the issue is not rotation i think, it is Tick on xAxes.
I think this link can help you :
https://www.chartjs.org/docs/latest/axes/styling.html#tick-configuration
also
Chart.js: evenly distribute ticks when using maxTicksLimit
xAxes: [{
ticks: {
autoSkip: false, // Skip or not?
maxTicksLimit: 30 // How much?
}
}]
and rotation just can help as #timclutton said here : https://stackoverflow.com/a/58275468/7514010

Flot Chart Bar spacing

I am using flotchart JS for showing bar graphs. However, I can't seemed to fix the spacing between bars.
I have enabled panning already. However, sets the width of the bar according to the placeholder. How can set each bar's spacing according to its label?
this is my code:
$.plot("#graph", [ data ], {
series: {
bars: {
show: true,
barWidth: 0.6,
align: "center"
}
},
xaxis: {
mode: "categories",
showTicks: false,
gridLines: false,
panRange: [0,null],
},
yaxis: {
panRange: [0, null],
plotPan: false //pan axis is allowed for plot pan
},
pan: {
interactive: true,
mode: "smart",
active: true
}
});

An alternative solution to your problem could be to rotate the tick labels for example by using the tickrotor plugin:
xaxis: {
mode: "categories",
showTicks: false,
gridLines: false,
panRange: [0,null],
rotateTicks: 90
},
You may need to increase the height of the chart since the labels now take up more space. See this fiddle for a full example.

You can achieve this by limiting the number of bars shown at once by giving a max property for the xaxis:
xaxis: {
mode: "categories",
showTicks: false,
gridLines: false,
panRange: [0,null],
max: 7, // set according to your needs, maybe dynamic depending on chart width
min: 0
},
You then have to use panning to see the other bars. See this fiddle for an example.

Chart js Backgroundimage Scaling

Hi i'm quite new to JS and looking for an easy way to show a custom map with my own backgroundimage and several points with x-y-coordinates on it.
At first it worked quite well using the "line"-chart-type of chart.js (v2.5) with disabled showScale()-option and fixed axes-max/min-values.
My problem is that the backgroundimage is not rescaling properly when i change the window-size or show/hide the legend of the chart.
Here is my JS-code for creating the chart:
function initMap() {
scatterChart = new Chart(document.getElementById("scatterChart"), {
responsive: true,
type: 'line',
data: {
/*datasets: [
{
}
]
*/
},
showScale: false,
options: {
scales: {
yAxes: [{
display: false,
ticks: {
max: y_max,
min: 0,
stepSize: 0.1
}
}],
xAxes: [{
display: false,
type: 'linear',
position: 'bottom',
ticks: {
max: x_max,
min: 0,
stepSize: 0.1
}
}]
},
onClick: function (evt) {
var activePoint = scatterChart.getElementAtEvent(evt);
},
legend: {
position: 'right',
labels: {
fontSize: 15
}
},
}
});
}
HTML:
<canvas id="scatterChart" style="width: 1920px; height: 1080px; background-image:url('media/map_background.jpg'); background-size: 100% 100%;"></canvas>
Here are two images showing the effect:
https://1drv.ms/i/s!As59C5Mmd0nahr1zP4rjwI5KobaM3Q
https://1drv.ms/i/s!As59C5Mmd0nahr10KwUCJ4wpvfn4_g
What can i do to get a proper rescaling (points should always be shown on the same position on the map regardless of windowsize or enabled/disabled legend)?

Have you tried using the maintainAspectRatio property and setting it to true? That should hopefully fix your window resize issue.
The only way to fix the legend issue is to use a legend that is external to the canvas because the legend takes up space in the canvas so the chart is squished horizontally (there is no layering concept in a canvas). See this example for how to generate an external legend.
You must use the legendCallback property and the .generateLegend() prototype method.