title: three.js dom id of canvas element used for webgl renderer
body: <p>I'd like to get the id of the canvas element automatically created by three.js.</p>
  
  <p>Alternately, I would be equally happy (perhaps more so) with the ability to pass along a preexisting canvas element id during construction.</p>
  
  <p>After researching, I tried this:</p>
  
  <pre><code>renderer = new THREE.WebGLRenderer( { canvas: my_canvas } );
  </code></pre>
  
  <p>without success (it is from a pretty old build, but was hoping it would work). Perhaps some parameter syntax has changed since 2 years ago?</p>
  
  <p>(my_canvas being the id of the canvas, also tried passing along the context, no luck)</p>
  
  <p>Finally I tried:</p>
  
  <pre><code>document.getElementsByTagName('canvas');
  </code></pre>
  
  <p>which returned nothing... that was a puzzler and the proverbial straw that led me to post here.</p>
  
  <p>Any insight appreciated, thanks! (I now have voting rights)</p>