ChartJs line chart repaint glitch while hovering o

问题:

I have the following code leveraging the ChartJS library.

/*assume the tags in the right place */

<canvas id="graph1" width="300" height="300"></canvas>

var ctx = $("#graph1").get(0).getContext("2d");
var myChart = new Chart(ctx).Line(graph1Generator("day"));

... everything works fine, but after adding the following event handler to clear and repaint the same chart with different data, a glitch occurs.

weekButton.addEventListener("click", function(){
    ctx.clearRect (0, 0, 300, 300);
    ctx.canvas.width = 300;
    ctx.canvas.height = 300;
    myChart = new Chart(ctx).Line(graph1Generator("week"));

This code does successfully redraw the chart with the new data, but when I hover over it, it does some very strange "flashbacks" to the old chart that it was supposed to clear. This makes me believe that it didn't clear the old one.

回答1:

Here is an update to your fiddle. The primary change (other than fixing the function name typo) is to add

myChart.destroy();

before lines like

myChart = new Chart(ctx).Line(...);

The .destroy() method gets rid of the event handler registrations etc, so you shouldn't see those weird "ghost charts" when you mouse over the graphics.