API

Drupal form API states can support multiple values.  

E.g.

$form['field_something']['#states'] = [
  'visible' => [
    ':input[name="field_else[0][target_id]"]' => [
      ['value' => 'one'],
      ['value' => 'two'],
      ['value' => 'three'],
      ['value' => 'four'],
    ],
  ],
];

This also applies to:

• Drupal 7
• Drupal 8
• Drupal 9
• Drupal 10

Configuration Synchronization

Drupal 8 has a really great configuration synchronization system, and is great for syncing up different environments.  When creating new modules and adding new fuctionality I really enjoy working with Drupal 8's configuration synchronization tool.  Not only does this tool take the guesswork out of updates that need to be made on other environments.  The configuration synchronization also allows for all changes to be documented.  

Wow, what a great little API.  Exchange Rates API is a free API that helps with currency conversion rates.  

All that needs to be sent is the base currency and the currency that you want to convert.  Then the conversion rate is returned.  Making it simple. 

Example

GET Request: https://api.exchangeratesapi.io/latest?base=USD&symbols=GBP

Result: {"base":"EUR","rates":{"USD":1.1264,"GBP":0.86168},"date":"2019-04-11"}