title: change transparent color into white in html2canvas
body: <p>I am using javascript library <a href="http://html2canvas.hertzen.com" rel="noreferrer">html2canvas</a> to save the table of my project. It works fine but when I save the image it shows transparent background color for PNG and background color black for jpeg.
  Here is what I did:</p>
  
  <pre><code>&lt;script&gt;
          window.onload = function(){
                html2canvas(document.getElementById("tablePng"),{
                      onrendered: function(canvas){
                      var img = canvas.toDataURL('image/jpeg');
                      $('#saveTable').attr('href',img);
                    }
                });
        };
  &lt;/script&gt;
  </code></pre>
  
  <p>Doing these above will save the images but the background colour will be black and when changing <code>var img = canvas.toDataURL('image/png');</code> the background will be transparent.
  And adding background as In documentation says:</p>
  
  <pre><code>    &lt;script&gt;
          window.onload = function(){
                html2canvas(document.getElementById("tablePng"),{
                      background: "#fff",
                      onrendered: function(canvas){                     
                      var img = canvas.toDataURL('image/jpeg');
                      $('#saveTable').attr('href',img);
                    }
                });
        };
  &lt;/script&gt;
  </code></pre>
  
  <p>will change nothing... give transparent.</p>
  
  <p>So how do I change the background ground color so that the images saved will be readable easily?</p>