function viewProducts() {
  var products_data = document.getElementById('howtos_products_data').innerHTML;
  document.getElementById('howtos_data_container').innerHTML = products_data;
  document.getElementById('howtos_comments_tab').className = '';
  document.getElementById('howtos_products_tab').className = 'tab_active';
}

function viewComments() {
  var comments_data = document.getElementById('howtos_comments_data').innerHTML;
  document.getElementById('howtos_data_container').innerHTML = comments_data;
  document.getElementById('howtos_products_tab').className = '';
  document.getElementById('howtos_comments_tab').className = 'tab_active';
}