Be clear about "use strict" in JavaScript files

Problem/Motivation

There is a code example and passing mention of the use of strict mode in JavaScript files, but no clear statement that use strict should be included in all JS files except modules.

Benefits

Clarity. An example issue where it was not clear if use strict should be included is 📌 Remove "use strict" statements from JS files Active .

Three supporters required

1. https://www.drupal.org/u/ → {userid} (yyyy-mm-dd they added support)
2. https://www.drupal.org/u/ → {userid} (yyyy-mm-dd they added support)
3. https://www.drupal.org/u/ → {userid} (yyyy-mm-dd they added support)

Proposed changes

1. JavaScript coding standards →

None.

All JavaScript must be written in strict mode. Include "use strict"; in every file except JavaScript modules.

Remaining tasks

2. Add supporters
3. Create a Change Record
4. Review by the Coding Standards Committee
5. Coding Standards Committee takes action as required
6. Discussed by the Core Committer Committee, if it impacts Drupal Core
7. Final review by Coding Standards Committee
8. Documentation updates
   1. Edit all pages
   2. Publish change record
   3. Remove 'Needs documentation edits' tag
9. If applicable, create follow-up issues for PHPCS rules/sniffs changes

For a full explanation of these steps see the Coding Standards project page →