title: In Javascript how can I set rgba without specifying the rgb?
body: <p>I have an HTML element whose background colour is set with rgba()</p>
  
  <pre><code>&lt;div style="background-color: rgba(2,100,100,0);"&gt; &lt;/div&gt;
  </code></pre>
  
  <p>Then I have a timer that makes the background slowly fade in by changing the opacity value of the element in javascript</p>
  
  <pre><code>myEle.style.backgroundColor = "rgba(x,x,x,0.1)"; // I have to know the rgb values to update the alpha value
  </code></pre>
  
  <p><strong>Is there a way to set the a value of rgba() without changing/knowing the rgb values?</strong></p>
  
  <p>Maybe I can do something like this?</p>
  
  <pre><code>var r = myEle.style.r;
  var g = myEle.style.g;
  var b = myEle.style.b;
  myEle.style.backgroundColor = "rgba("+r+","+g+","+b+",0.1)";
  </code></pre>