ChartJs mouse hover bug (showing previous charts)

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.

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();

It is not bug. Basically you were creating a new graph each time. What you need here is to update graph instead of drawing a new one on that canvas. This can be done using the following code.

 if(typeof Graph ==="undefined"){
       window.Graph = new Chart(Graph_ctx, Graph_config);
 }else{
       //updating with new chart data
       window.Graph.config=Graph_config;
       //redraw the chart
       window.Graph.update();
 }

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.