title: Chart.js: chart not displayed
body: <p>I'd like to use <strong><a href="http://www.chartjs.org/" rel="noreferrer">Chart.js</a></strong> to create stunning charts into a webpage.</p>
  
  <p>Following the documentation, I wrote the code as follows:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  
  &lt;head&gt;
      &lt;meta charset="utf-8"/&gt;
      &lt;title&gt;Chart.js demo&lt;/title&gt;
      &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/0.2.0/Chart.min.js" type="text/javascript"&gt;&lt;/script&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
      &lt;script&gt;
          var pieData = [
              {
                  value: 20,
                  color:"#878BB6"
              },
              {
                  value : 40,
                  color : "#4ACAB4"
              },
              {
                  value : 10,
                  color : "#FF8153"
              },
              {
                  value : 30,
                  color : "#FFEA88"
              }
          ];
          // Get the context of the canvas element we want to select
          var countries= document.getElementById("countries").getContext("2d");
          new Chart(countries).Pie(pieData);
      &lt;/script&gt;
  
      &lt;h1&gt;Chart.js Sample&lt;/h1&gt;
      &lt;canvas id="countries" width="600" height="400"&gt;&lt;/canvas&gt;
  &lt;/body&gt;
  
  &lt;/html&gt;
  </code></pre>
  
  <p>Which is the reason why the chart doesn't appear?</p>