When importing tags, or when in development, you would sometimes need to delete all terms from a vocabulary. This snippet does the trick for you.
Twig is the theme engine in drupal 8 sites. This snippet how to link to nodes correctly, without using preprocess functions to do it.
Twig comes with quite some handy functionalities. Date formatting is an example. In this snippet an example of how to show the created date in a drupal 8 time format. 
Sometimes you need a body text that is trimmed. No need to install contrib modules.
Use global theme javascript only in a few occasions. You should make sure javascript is only used on the right places. This snippet shows you how to load javascript when a specific view is loaded only.
Batch processes give you a hard time when using them for the first time. This module example will handle every aspect of it!
A much needed functionality is how you get the url of an image style form the uri (f.e. in a node object). This snippets helps you accomplish this.
When importing content, it is really important you also think about meta tags on your import. Here's how to save them to nodes.
Drupal 8 is becoming more and more API-first based. This means a lot of imports and exports of data will be done. A thing you might face here, is the updating of entity reference fields is a bit tricky. Here I'll show you how it is done.
Paragraphs give great power to drupal 8. This code will show you how you can add them programmatically, for example when importing stuff.