I have two HTML buttons, each linked to a specific JavaScript function. The first button triggers a function codded like so:
function add() {
var newScript = document.createElement("script");
newScript.src = "https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js";
document.head.appendChild(newScript);
}
The second button triggers the following function:
function draw() {
const ctx = document.getElementById('myChart').getContext('2d');
const 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: {
y: {
beginAtZero: true
}
}
}
});
In function number 2, I am using a sample from www.chartjs.org. To work, it needs the page to have loaded the script referred to in the first function.
After clicking on the button 1 then on the button 2, I am expecting to see in my head element a script element, src=https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js, which I do see, via the browser console.
On my page, I am expecting to see (after clicking on my second button) a graph, produced by the ChartJS code. This very element is missing. Instead, I have an error in my console, saying: 'Chart is not defined at HTMLButtonElement.draw'
Why do I have this error? Why is my chart not showing up?
Thank you for stopping by :) (y)
One hacky solution is to just include the entire script in your function. i.e.
function add() {
/*!
* Chart.js v2.9.4
* https://www.chartjs.org
* (c) 2020 Chart.js Contributors
* Released under the MIT License
*/
//The entire contents of https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.min.js pasted here
}
Just add html script element, before the your script is evaluated.
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script>
<script>
function draw() {
// your draw function
}
</script>
Related
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.
I want to use ChartJS so I can display charts on my website, but I don't want the JavaScript to be separate from the html. I am using pug (jade) as my view engine which I know is working properly.
First I linked ChartJS in my index.pug file and created my canvas:
html
head
link(rel='stylesheet', href='/stylesheets/styles.css', type='text/css')
script(type="text/javascript", src='https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.6.0/Chart.bundle.min.js')
script(type="text/javascript", src='/javascripts/chart.js')
title= title
body
h1= message
canvas#myChart(width='400', height='400')
Next, In my chart.js file I did:
var ctx = document.getElementById("myChart").getContext('2d');
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
}
}]
}
}
});
For some reason, the chart isn't being displayed, however if I use script tags and put the JavaScript directly in the pug file it works fine. I know that the JavaScript file is being linked correctly because I checked it using an alert. Any ideas on why my chart isn't being displayed?
Add your code inside the document ready like this:
$( document ).ready(function() {
// your chart code goes here.
});
I am using the official chart.js atmosphere package in my meteor application. I've tried running an example chart to see if I can pull it up however I am getting an issue saying "ReferenceError: Chart is not defined"
Here are the steps I took to installing the atmosphere package and running the code to produce the chart.
Installed the package with meteor add chart:chart
In my HTML I added the canvas tag calling the chart with it's informaiton
In the JS I added the function that creates the chart along with its relevant information
When I go to the page however, I just get an empty 400x400 image which is the canvas but there is no content there where the chart is supposed to be. Could someone assist me in figuring out what step I'm missing in order to get the chart to appear?
HTML
<template name="Home_page">
<canvas id="myChart" width="400" height="400"></canvas>
</template>
JS
import './home-page.html';
Template.Home_page.onRendered(function homePageOnRendered() {
var ctx = document.getElementById("myChart").getContext("2d");
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
}
}]
}
}
});
});
Ok I forgot to add
import Chart from 'chart.js'
in the top of my js file. That fixed it.
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
}
}]
},
}
});
I'm attempting to call Chart.js's addData method from a signalR callback in order to dynamically add data to a chart based on server inputs. However, when the callback is triggered, the addData method on Chart.js is throwing an exception:
Uncaught TypeError: window.myChart.addData is not a function
Javascript:
var ctx = $("#myChart");
window.myChart = new Chart(ctx, {
type: 'line',
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
}
}]
}
},
responsive: true
});
$(function () {
var chart = $.connection.chartHub;
chart.client.addPointToChart = function () {
window.myChart.addData([20], "Magenta");
};
$.connection.hub.start().done(function () {
chart.server.start();
});
});
C# (hub code)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.AspNet.SignalR;
namespace dvvWeb.Hubs
{
public class ChartHub : Hub
{
public void Start()
{
while (true)
{
Clients.All.addPointToChart();
System.Threading.Thread.Sleep(10000);
}
}
}
}
According to the documentation you should change your dataset directly and call update:
.update(duration, lazy) function to update your datas
// duration is the time for the animation of the redraw in miliseconds
// lazy is a boolean. if true, the animation can be interupted by other animations
myLineChart.data.datasets[0].data[2] = 50; // Would update the first dataset's value of 'March' to be 50
myLineChart.update(); // Calling update now animates the position of March from 90 to 50.
I did a little test function on this fiddle:
setInterval(function(e) {
console.log(myDoughnutChart.data.datasets[0]);
myDoughnutChart.data.datasets[0].data.push(15);
myDoughnutChart.update();
}, 1000);
https://jsfiddle.net/Tintin37/weLoqyby/
Opened issue : https://github.com/chartjs/Chart.js/issues/1997
EDIT
For real time chart (I'm using signalr too, I use visjs)
http://visjs.org/examples/graph2d/15_streaming_data.html
Have a great day !