JSnippet

This module allows you to create Javascript snippets for use on a site. It supports including either javascript code added to the text area, or a URL to a third party resource. Any snippet created will be wrapped in a Drupal Behavior, written to the public file system, and made available through Drupal's libraries system. Snippets are stored as configuration entities and are exportable to the site's code base.

To use a snippet you can add an entity reference to the Snippet configuration entity and use it's custom Snippet formatter for display. This will attach the javascript library during rendering of the content entity where the entity reference resides, adding the snippet to the DOM.

This allows for tight control of how javascript gets added to a site, rather than allowing content editors to paste stuff in ad-hoc.