title: What is pixel width and length for jspdf's default 'a4' format?
body: <p>What is the size in pixels for jspdf's 'a4' format?
  I want to add an image to pdf so it will take full width of the document.</p>
  
  <pre><code>new jsPDF('p', 'pt', 'a4');
  </code></pre>