title: How to clear a chart from a canvas so that hover events cannot be triggered?
body: <p>I'm using Chartjs to display a Line Chart and this works fine:</p>
  
  <pre><code>// get line chart canvas
  var targetCanvas = document.getElementById('chartCanvas').getContext('2d');
  
  // draw line chart
  var chart = new Chart(targetCanvas).Line(chartData);
  </code></pre>
  
  <p>But the problem occurs when I try to change the data for the Chart.  I update the graph by creating a new instance of a Chart with the new data points, and thus reinitializing the canvas. </p>
  
  <p>This works fine. However, when I hover over the new chart, if I happen to go over specific locations corresponding to points displayed on the old chart, the hover/label is still triggered and suddenly the old chart is visible.  It remains visible while my mouse is at this location and disappears when move off that point.  I don't want the old chart to display. I want to remove it completely.</p>
  
  <p>I've tried to clear both the canvas and the existing chart before loading the new one.  Like:</p>
  
  <pre><code>targetCanvas.clearRect(0,0, targetCanvas.canvas.width, targetCanvas.canvas.height);
  </code></pre>
  
  <p>and</p>
  
  <pre><code>chart.clear();
  </code></pre>
  
  <p>But none of these have worked so far.  Any ideas about how I can stop this from happening?</p>