$field_type_manager = \Drupal::service('plugin.manager.field.field_type');
$class = $field_type_manager->getDefinition('entity_reference')['class'];this will show you info
Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem so you can check there settings and code for this field type.
In drupal 7 when you moved modules from one directory to other, usually running drush rr (registry rebuild) would work, maybe you would need to clear caches. In drupal 8, this wont help. Paths are saved in APC and you will probably need to restart server.
For someone maybe
For selenium there is also selenium command runner, called selenium side runner, as I pointed out some tips about how to use NEW Selenium IDE here, here are tips on how to use it with CLI or with some CI/CD.
As it is often referred online as "new selenium IDE 2019" lets sum up some tips how to use it. It can record your actions and put them in its UI, but you will often need to change it and refine it to get something useful.
If you used google pagespeed and got "Enable Text Compression" you will fix this with uncommenting this lines in your nginx.config (or adding them)
Not many tutorials cover this often used practices in drupal 8, so check the differences betweeen self and this
https://stackoverflow.com/questions/5197300/new-self-vs-new-static
I was wondering how PHP gets compiled to OpCodes and how does that all work, there is a nice post that talks about OpCode caching in general (a bit outdated now) and also gives a good example of how php code is tokenized for OpCode https://support.cloud.en
Reading docs about drupal_add_js you might think you can add JS to header of html, but only thing you can choose is header or footer of your theme (as region), to add JS to header tag, you need to use
In this post I will determine how many DB tables does each option you choose make.
Lets start with NODE, make a basic node, with just title and body, when we enter data for it, it will populare 6 tables.
1. node
2. node_revision
3. node__body
4. node_revision__body
5. node_field_data
6. node_field_revision
Just go here and check how to do that
https://modulesunraveled.com/blog/install-drush-7-and-8-and-automatical…
also for drupal 7 dont use drush 9 with drush launcher as it is useless and most of the useful functions you had are gone in drush 9.