ChartJs mouse hover bug (showing previous charts)

Question

I think my issue is a known one, everytime I make a new chart and hover my mouse over some points in the canvas, the old charts flash in and out all the time. Here's one of the threads I followed to try and fix it, but nothing seems to work. I tried re-appending the canvas, using destroy, clear, if statements which should clear it, but nothing.

Here's my code:

var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
    type: 'line',
    data: {
        labels: chartjsDate,
        datasets: [{
            label: 'temp',
            data: chartjsTemp,
            backgroundColor: "rgba(240,240,240,0.5)"
        }]
    }
});

I tried adding myChart.destroy(); before and after that code, even if(myChart!=null){myChart.destroy();}, but still nothing. Any help on how to fix it would be appreciated. All other threads I found are quite old and their solutions don't work.

Edit: Some stuff I tried, to no avail:

var myChart;
if (myChart != undefined || myChart !=null) {
    myChart.destroy();
}

Answer 1

Solved! I added this above the javascript code:

var button = document.getElementById("submitButton");
submitButton.addEventListener("click", function(){
    myChart.destroy();
});

And changed my submit button to have the id "submitButton", like this:

<input type="submit" class="btn btn-danger" id="submitButton" value="Send" />

This way, everytime you press the submit button, it destroys the previous chart. The weird thing is that when trying to use myChart.destroy(); I got errors.

Answer 2

I also had this problem. To solve it, you first have to declare myChart variable globally and then try this way.

//var my chart declare globally.  
let chartData = {
        type: 'line',
        data: {
            labels: chartjsDate,
            datasets: [{
                label: 'temp',
                data: chartjsTemp,
                backgroundColor: "rgba(240,240,240,0.5)"
            }]
        }
        if (typeof(this.myChart) != "undefined") {
            this.myChart.destroy();
        }

        const ctx = this.renderRoot.querySelector('#chart-canvas').getContext('2d');
        this.myChart = new Chart(ctx, chartData);
        this.myChart.update();

Answer 3

Above solutions are working for me but when I have two charts on the same page, Only one is showing. Other charts are becoming empty. Here is the solution for that.

  var ctx = document.getElementById("bar-chart").getContext("2d");  

  //Destroy the previous chart;
  //Rename the "bar" according to your component
  if(window.bar != undefined)
  window.bar.destroy();
  window.bar = new Chart(ctx , {});

if you don't change the "bar", only one chart will show in your page.