💅 Improve noSyncScripts rule

[THernandez03]

Environment information

» npx @biomejs/biome rage --linter
CLI:
  Version:                      2.3.6
  Color support:                true

Platform:
  CPU Architecture:             x86_64
  OS:                           linux

Environment:
  BIOME_LOG_PATH:               unset
  BIOME_LOG_PREFIX_NAME:        unset
  BIOME_CONFIG_PATH:            unset
  BIOME_THREADS:                unset
  NO_COLOR:                     unset
  TERM:                         xterm-256color
  JS_RUNTIME_VERSION:           v25.2.1
  JS_RUNTIME_NAME:              node
  NODE_PACKAGE_MANAGER:         npm/11.6.2

Biome Configuration:
  Status:                       Loaded successfully
  Path:                         biome.jsonc
  Formatter enabled:            true
  Linter enabled:               true
  Assist enabled:               true
  VCS enabled:                  false

Linter:
  JavaScript enabled:           unset
  JSON enabled:                 unset
  CSS enabled:                  unset
  GraphQL enabled:              unset
  Recommended:                  false
  Enabled rules:
    nursery/noSyncScripts

Workspace:
  Open Documents:               0

Rule name

noSyncScripts

Playground link

https://github.com/THernandez03/biome-noSyncScripts

Why This is Incorrect

Module Scripts Are Already Deferred

According to the MDN Web Docs - JavaScript Modules:

3. Modules are deferred automatically

Modules are automatically executed in defer mode. This means that:

• Module scripts are downloaded in parallel to parsing the HTML
• Module scripts are executed after the document has been parsed
• The relative order of multiple module scripts is preserved

Expected result

The noSyncScripts rule should be updated to:

1. Skip validation for <script> tags with type="module"
2. Only flag classic <script> tags without defer or async attributes
3. Optionally provide an informational message explaining that module scripts are already deferred

Code of Conduct

• I agree to follow Biome's Code of Conduct

[ematipico]

Thank you @THernandez03

A couple of things:

• for points 1 and 2, can you also share why?
• can you update the reproduction by adding a valid file? The rule, as per documentation, is only available in JSX

[Netail]

type="module" indeed does not seem to block rendering; https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/script#blocking. The same effect as defer

The rule, as per documentation, is only available in JSX

Also the html analyzer actually, but those don't seem to be displayed on the website yet.

[THernandez03]

Hey guys, first of all, thanks for the quick response and thanks for the awesome work you're doing 🙌.

I just updated the issue description for better understanding the points