title: Show placeholder text in empty input fields
body: <p>How it is possible that during <code>onfocus</code> (on input field) input default value seen like it is disabled but on input field could be written anything like default value isn't exists ?</p>
  
  <p>here is simple html =></p>
  
  <pre><code>&lt;input type="text" id="x"&gt;
  </code></pre>
  
  <p>and javascript =></p>
  
  <pre><code>document.getElementById("x").onfocus = function(){
  this.style.opacity = 0.5;
  }
  </code></pre>
  
  <p>but I couldn't do what I want.</p>