Add script to cleanup redundant BCD overrides

package.json

@@ -33,7 +33,8 @@
     "test:types": "npm run --workspaces test:types && tsc",
     "test": "npm run test:caniuse -- --quiet && npm run test:schema && npm run test:specs && npm run test:format && npm run test:dist && npm run test --workspaces && npm run test:lint",
     "update-drafts": "tsx scripts/update-drafts.ts",
-    "migrate-to-bcd": "tsx scripts/migrate-to-bcd.ts"
+    "migrate-to-bcd": "tsx scripts/migrate-to-bcd.ts",
+    "cleanup-bcd-overrides": "tsx scripts/cleanup-bcd-overrides.ts"
   },
   "devDependencies": {
     "@eslint/js": "^9.15.0",

scripts/cleanup-bcd-overrides.ts

@@ -0,0 +1,105 @@
+import { setLogger } from "compute-baseline";
+import { Compat, Feature } from "compute-baseline/browser-compat-data";
+import { fdir } from "fdir";
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { isDeepStrictEqual } from "node:util";
+import winston from "winston";
+import YAML from "yaml";
+import yargs from "yargs";
+import {checkForStaleCompat} from "./dist.ts";
+
+const compat = new Compat();
+
+const argv = yargs(process.argv.slice(2))
+  .scriptName("cleanup-bcd-overrides")
+  .usage(
+    "$0 [paths..]",
+    "Remove `compat_features` from `.yml` files that have an equivalently tagged set of features in @mdn/browser-compat-data",
+    (yargs) =>
+      yargs.positional("paths", {
+        describe: "Directories or files to check/update.",
+        default: ["features"],
+      }),
+  ).argv;
+
+const logger = winston.createLogger({
+  level: argv.verbose > 0 ? "debug" : "warn",
+  format: winston.format.combine(
+    winston.format.colorize(),
+    winston.format.simple(),
+  ),
+  transports: new winston.transports.Console(),
+});
+
+let exitStatus = 0;
+
+setLogger(logger);
+
+const tagsToFeatures: Map<string, Feature[]> = (() => {
+  // TODO: Use Map.groupBy() instead, when it's available
+  const map = new Map();
+  for (const feature of compat.walk()) {
+    for (const tag of feature.tags) {
+      let features = map.get(tag);
+      if (!features) {
+        features = [];
+        map.set(tag, features);
+      }
+      features.push(feature);
+    }
+  }
+  return map;
+})();
+
+function cleanup(sourcePath: string): void {
+  const source = YAML.parseDocument(
+    fs.readFileSync(sourcePath, { encoding: "utf-8" }),
+  );
+  const { name: id } = path.parse(sourcePath);
+
+  // Collect tagged compat features. A `compat_features` list in the source
+  // takes precedence, but can be removed if it matches the tagged features.
+  const taggedCompatFeatures = (tagsToFeatures.get(`web-features:${id}`) ?? [])
+    .map((f) => `${f.id}`)
+    .sort();
+
+  const data = source.contents.get("compat_features");
+
+  if (data) {
+    const features = data.items.map((item) => item.value).sort();
+    if (isDeepStrictEqual(features, taggedCompatFeatures)) {
+      const comment = data.comment || data.commentBefore;
+      if (comment) {
+        source.comment = (source.comment || "") + comment;
+      }
+      source.contents.delete("compat_features");
+      fs.writeFileSync(sourcePath, source.toString({ lineWidth: 0 }));
+      logger.info(`${id}: removed compat_features in favor of tag`);
+    }
+  }
+}
+
+function main() {
+  const filePaths: string[] = argv.paths.flatMap((fileOrDirectory) => {
+    if (fs.statSync(fileOrDirectory).isDirectory()) {
+      return new fdir()
+        .withBasePath()
+        .filter((path) => path.endsWith(".yml"))
+        .crawl(fileOrDirectory)
+        .sync();
+    }
+    return fileOrDirectory.endsWith(".yml") ? fileOrDirectory : [];
+  });
+
+  for (const sourcePath of filePaths) {
+    cleanup(sourcePath);
+  }
+}
+
+if (process.argv[1] === fileURLToPath(import.meta.url)) {
+  checkForStaleCompat();
+  main();
+  process.exit(exitStatus);
+}

scripts/dist.ts

@@ -56,7 +56,7 @@ setLogger(logger);
  * one pinned in `package.json`. BCD updates frequently, leading to surprising
  * error messages if you haven't run `npm install` recently.
  */
-function checkForStaleCompat(): void {
+export function checkForStaleCompat(): void {
   const packageBCDVersionSpecifier: string = (() => {
     const packageJSON: unknown = JSON.parse(
       fs.readFileSync(process.env.npm_package_json, {