Add feature for discouraged import assertions (#2565)

Co-authored-by: Patrick Brosset <[email protected]>

Author: ddbeck

features/css-modules.yml

@@ -1,3 +1,3 @@
 name: CSS import attributes
-description: 'Module `import … with { type: "css" } statements load CSS modules as constructable stylesheets. Also known as CSS module scripts and formerly known as import assertions.'
+description: 'Module `import … with { type: "css" } statements load CSS modules as constructable stylesheets. Also known as CSS module scripts.'
 spec: https://html.spec.whatwg.org/multipage/webappapis.html#css-module-script

features/import-assertions.yml

@@ -0,0 +1,13 @@
+name: Import assertions
+description: 'Module `import … assert { type: "json" }` and `import … assert { type: "css" }` JavaScript statements load JSON and CSS data.'
+spec: https://github.com/tc39/proposal-import-attributes/tree/abca60286360b47f9a6be25a28f489c2cb157beb
+discouraged:
+  according_to:
+    - https://github.com/tc39/proposal-import-attributes/pull/131
+  alternatives:
+    - css-modules
+    - json-modules
+compat_features:
+  - javascript.statements.import.import_assertions
+  - javascript.statements.import.import_assertions.type_css
+  - javascript.statements.import.import_assertions.type_json

features/import-assertions.yml.dist

@@ -0,0 +1,10 @@
+# Generated from: import-assertions.yml
+# Do not edit this file by hand. Edit the source file instead!
+
+status:
+  baseline: false
+  support: {}
+compat_features:
+  - javascript.statements.import.import_assertions
+  - javascript.statements.import.import_assertions.type_css
+  - javascript.statements.import.import_assertions.type_json

features/json-modules.yml

@@ -1,5 +1,5 @@
 name: JSON import attributes
-description: 'Module `import … with { type: "json" }` statements load JSON data. Also known as JSON module scripts and formerly known as import assertions.'
+description: 'Module `import … with { type: "json" }` statements load JSON data. Also known as JSON module scripts.'
 spec: https://html.spec.whatwg.org/multipage/webappapis.html#json-module-script
 group: json
 # TODO: Tag javascript.statements.import when https://github.com/web-platform-dx/web-features/issues/1173 is resolved.

scripts/specs.ts

@@ -96,6 +96,10 @@ const defaultAllowlist: allowlistItem[] = [
     [
         "https://immersive-web.github.io/webvr/spec/1.1/",
         "Allowed because this is the legacy spec that defines WebVR."
+    ],
+    [
+        "https://github.com/tc39/proposal-import-attributes/tree/abca60286360b47f9a6be25a28f489c2cb157beb",
+        "Allowed because import assertions were replaced in-place by import attributes. Remove this exception when javascript.statements.import.import_assertions is dropped from BCD in June 2026."
     ]
 ];