Theming : enable Twig templates Debug

Enable debugging

You enable Twig Debugging in sites/default/services.yml.

(If services.yml does not yet exist; copy default.services.yml and rename it to services.yml.)

parameters:

 twig.config:

  debug: true

Printing variables

{{ dump() }}

{{ dump(var) }}

Or If you have Devel's kint:

{{ kint() }}

Via Drush (On drupal 7, Not for D8)

drush vset theme_debug 1

Configuration override For theming and Integration.

To optimize performence, drupal compress and aggregate CSS / JS files. But for front side development we need to disable this function. You can do that from /admin/config/development/performance , and also via setting.php.

Disable CSS / JS preprocess by settings.php

$config['system.performance']['css']['preprocess'] = 0;

$config['system.performance']['js']['preprocess'] = 0;