function clean(node)
  {
    for(var n = 0; n < node.childNodes.length; n ++)
    {
      var child = node.childNodes[n];
      if
      (
        child.nodeType === 8 || (child.nodeType === 3 && !/\S/.test(child.nodeValue))
      )
      {
        node.removeChild(child);
        n --;
      }
      else if(child.nodeType === 1)
      {
        clean(child);
      }
    }
  }
clean(document);