In order to structure my code, I try to implement module.
I would like to create a class that would be able to create charts from ChartJs library.
Basically, I have three files
Index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="https://cdn.jsdelivr.net/npm/chart.js@2.8.0"></script>
</head>
<body>
<div>
<canvas id="test"></canvas>
</div>
</body>
<script type="module" src="index.js"></script>
</html>
chartjs.js
"use strict";
export default class Chart {
constructor(ctx, type) {
this.type = type;
this.ctx = ctx;
}
setOptions(options) {
this.options = options;
}
setData(data) {
this.data = data;
}
drawChart() {
var chart = new Chart(this.ctx, {
// The type of chart we want to create
type: this.type,
// The data for our dataset
data: this.data,
// Configuration options go here
options: this.options,
});
return {
chart: chart,
};
}
}
index.js
import Chart from "/chart.js";
var data = {
labels: ["January", "February", "March", "April", "May", "June", "July"],
datasets: [
{
label: "My First dataset",
backgroundColor: "rgb(255, 99, 132)",
borderColor: "rgb(255, 99, 132)",
data: [0, 10, 5, 2, 20, 30, 45],
},
],
};
var ctx = document.getElementById("test").getContext("2d");
var chartObj = new Chart(ctx, "line");
chartObj.setData(data);
chartObj.setOptions({});
var chart = chartObj.drawChart();
I have no errors.
I tried to create a function that will encapsulate the working code
test(ctx) {
console.log("🚀 ~ file: index.html ~ line 28 ~ ctx", ctx);
var chart = new Chart(ctx, {
// The type of chart we want to create
type: "line",
// The data for our dataset
data: {
labels: [
"January",
"February",
"March",
"April",
"May",
"June",
"July",
],
datasets: [
{
label: "My First dataset",
backgroundColor: "rgb(255, 99, 132)",
borderColor: "rgb(255, 99, 132)",
data: [0, 10, 5, 2, 20, 30, 45],
},
],
},
// Configuration options go here
options: {},
});
}
So my guess would be the fact that my canvas is not well instantiated but I don’t know why.
Could you please help me on that ?
Try renaming your custom class to something different then
Chart
. If I remember corrently someone else got the same issue and that fixed it