So I'm trying to make a JS function that uses ChartJS, the variable/data the fucntion gets, is a JSON object. The reason why I use try/catch is because the two lines under here:
let labels = json_data.data.map(e => e.StartTime);
let data = json_data.data.map(e => e.StatusId);
Isn't always set if there is any data they are set, but if not is the only one set
let data = json_data.message.map(e => e.message);
Unless on page load, then nothing is set.
The JSON object change when a <Select> dropdown is changed, and if there is data in one then the canvas is loaded, but if the user then select one with no data, I want the graft to be empty/destroyed, but I cant do this because I'm in a try catch, and if I define it in the catch too, then it says that the ID already is in use. What do I have to do to "reset/destroy" it in the catch?
function chartJSLoad(json_data) {
try {
let labels = json_data.data.map(e => e.StartTime);
let data = json_data.data.map(e => e.StatusId);
console.log(labels);
console.log(data);
var ctx = document.getElementById('canvaschartjs').getContext('2d');
var myChart = new Chart(ctx, {
data: {
datasets: [{
type: 'bar',
label: 'Bar Dataset',
data: data,
backgroundColor: 'rgba(0, 150, 90)',
borderColor: 'rgba(0, 255, 90)',
order: 2
}, {
type: 'line',
label: 'Line Dataset',
data: data,
backgroundColor: 'rgba(150, 0, 90)',
borderColor: 'rgba(255, 0, 90)',
order: 1
}],
labels: labels
},
options: {
maintainAspectRatio: false,
responsive: true,
scales: {
x: {
stacked: true,
},
y: {
stacked: true
}
}
}
});
} catch (error) {
if (typeof json_data !== 'undefined') {
myChart.destroy();
alert(json_data.message);
}
}
}
You can use the static method getChart to check if a chart with that context already exists, if it does you get that chart instance which you can destroy:
catch (error) {
if (typeof json_data !== 'undefined') {
let chart = Chart.getChart('canvaschartjs');
if (typeof chart !== 'undefined') {
chart.destroy()
}
alert(json_data.message);
}
}
Live example:
var options = {
type: 'line',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
borderColor: 'pink'
},
{
label: '# of Points',
data: [7, 11, 5, 8, 3, 7],
borderColor: 'orange'
}
]
},
options: {}
}
var ctx = document.getElementById('chartJSContainer').getContext('2d');
let myChart = new Chart(ctx, options);
let chart = Chart.getChart('chartJSContainer');
if (typeof chart !== 'undefined') {
chart.destroy() // Does not show anything because of this line, comment it out to show again
}<body>
<canvas id="chartJSContainer" width="600" height="400"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.6.0/chart.js"></script>
</body>