Develop Reference

chart.js function delay not affect my graph

I am asking you because I created a chart with chart.js and I would like to assign it a delay before it appears, after reading the docs and different forums I get the following code which unfortunately does not work. Thanking you in advance for your help!
var cts = document.getElementById('myDonutChart').getContext('2d');
var myDonutChart = new Chart(cts, {
type: 'doughnut',
data: {
labels:[
//requete sql
'Red',
'Blue',
'Yellow'
],
datasets: [{
label: '# of Votes',
data: [
//requete sql
12,
19,
3,
5,
2,
3
],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255, 99, 132, 1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
legend: { display: false },
responsive: false,
maintainAspectRatio: false,
animation: {
delay: 4000
}
}
});
Reading the doc gives me the result with the delay function or alone it doesn't work and the only solution I found was to add a setimout but I still wanted to find the solution to the delay problem

Chartjs is not showing charts in my Django project

I am trying to visualize data in my Django project using Chartjs. right now I'm only concerned with the visualize part and not the backend stuff but for some strange reason the charts refuses to display even though I took the boilerplate directly from the website just to display it before manipulating it.
<div id="chart_div" class="option-chart">
<canvas id="myChart" width="648" height="495"></canvas>
</div>
<script>
const ctx = document.getElementById('myChart');
const myChart = {
type : 'bar',
data : {
labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255, 99, 132, 1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options : {
scales: {
y: {
beginAtZero: true
}
}
}
};
</script>
As you can see from the code above. its boilerplate but I just cant get it to visualize.

I think you have not added the cdn link

Chart Js function (Chart.js) is stuck in a loop

I am trying to use Chart.js in my HTML document(main.html) by calling the the javascript function form a separate javascript file (home.js).
The HTML looks as follows:
{% block head %}
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.6.0/Chart.min.js"></script>
<script type="text/javascript" src="/static/js/home.js"></script>
{% endblock %}
{% block body %}
<div>
<canvas id='myChart'></canvas>
</div>
<script>
Chart(data, document.getElementById('myChart'))
</script>
The js file looks as follows:
function Chart(data, ctx){
console.log("JS")
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255, 99, 132, 1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
}
}
});
}
When I do that it somehow keeps executing the the function (ie. stuck in a loop, I checked that by using console.log('JS'). I did not figure out why it keeps doing that. The chart is never displayed.
If I add the function directly in the html in a tag it works flawlessly, but I'd rather want the js separate from the html.
I use flask as web framework and that is where the variable 'data' is coming from. Any tips or ideas?
Thanks and regards
PS: I don't use 'data' at the moment because I don't even get the chart running (it will be the result of db query later.

First, two problems unrelated to your infinite loop problem:
In main.html, the data param you are sending to Chart.js is undefined. Presumably you will fix that in your actual code.
In the selector you send to Chart.js, you are sending the canvas – document.getElementById('myChart') – when you should be sending the canvas context – document.getElementById('myChart').getContext('2d')
Once those are fixed, you could potentially be rendering a chart, but you get an infinite loop because you have called your own function Chart when that's also the name of the Chart.js function (where it says var myChart = new Chart(ctx, ...). Just change your function name to something else.
Here's an example where I just put in an empty array for data and changed your function name to drawChart.
function drawChart(data, ctx){
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255, 99, 132, 1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
}
}
});
}
drawChart([], document.getElementById('myChart').getContext('2d'))
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.6.0/Chart.min.js"></script>
<canvas id='myChart'></canvas>
NB: The script error that shows up in the console log is because of cross-origin scripting on StackOverflow and is something you can fix on your own site.

Installing chartjs in project without npm, bower or CDN

I am working on a graph page for a project and my client does not want me to use npm, bower or CDN. so my question is how would I use the chartjs library without using these options?
I tried using it this way:
var Chart = require(['../chartjs/Chart.js']);
var ctx = document.getElementById("bar-chart");
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
}
}
});
but I keep getting the following error:
Uncaught Error: Script error for "../chartjs/Chart.js".
Am I missing a step?

Try this
import chart from './chart';
console.log(chart);

How to draw Horizontal line on Bar Chart Chartjs

I have the following script of drawing bar chart and I wanna add horizontal line on particular y dot. I was trying following example link and I just substituted Chart.types.Line.extend with Chart.types.Bar.extend
but as a result I'm getting can not read property extend of undefined
So can someone help to implement above example which in the link properly or suggest another decision
my source code without horizontal line
var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero:true
},
}]
},
}
});

You can use Chart.js plugins to do that. Plugins let you handle specific events such as beforeUpdate or afterDraw and are also easy to implement :
Chart.pluginService.register({
afterDraw: function(chart) {
// Code here will be triggered ... after the drawing
}
});
An easy way to do it is to simply draw a line like you would you on a simple canvas element, after everything is drawn in your chart, using the lineTo method.
Here is a small example (and its related code) of how it would look like :

With the answer from #tektiv, your yAxis always starts at 0.
This is a working example without the use of yAxe.min, so
you can use it (for example, with beginAtZero:false) and the yAxe scales automatically with your data.
Line plugin:
var canvas = document.getElementById("barCanvas");
var ctx = canvas.getContext('2d');
Chart.pluginService.register({
afterDraw: function(chart) {
if (typeof chart.config.options.lineAt != 'undefined') {
var lineAt = chart.config.options.lineAt;
var ctxPlugin = chart.chart.ctx;
var xAxe = chart.scales[chart.config.options.scales.xAxes[0].id];
var yAxe = chart.scales[chart.config.options.scales.yAxes[0].id];
ctxPlugin.strokeStyle = "red";
ctxPlugin.beginPath();
lineAt = yAxe.getPixelForValue(lineAt);
ctxPlugin.moveTo(xAxe.left, lineAt);
ctxPlugin.lineTo(xAxe.right, lineAt);
ctxPlugin.stroke();
}
}
});
Chart:
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
lineAt: 14,
scales: {
yAxes: [{
ticks: {
beginAtZero:false
}
}]
},
}
});