title: 'optgroup' element label isn't reading the string after space
body: <p>Below when the code runs label doesn't read the string 'data' after space. I have tried with some CSS on optgroup element but it didn't make any change on its label.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var data = "Names of Meters";
  var func = function() {
    var options = 
        "&lt;optgroup label=" +data+ "&gt;"
          +'&lt;option value="Meter1" &gt;' + "Temperature" + '&lt;/option&gt;'
          +'&lt;option value="Meter2" &gt;' + "Wave" + '&lt;/option&gt;'
          +'&lt;option value="Meter3" &gt;' + "Wind Speed" + '&lt;/option&gt;'
        + "&lt;/optgroup&gt;";
    return options
    }
    document.getElementById("demo").innerHTML = func();</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>   &lt;select type='list' name='sensors' id ="demo" multiple&gt;&lt;/select&gt;</code></pre>
  </div>
  </div>
  </p>