feat(scripts): add split script

package.json

@@ -114,6 +114,7 @@
     "traverse": "tsx scripts/traverse.ts",
     "update-browser-releases": "tsx scripts/update-browser-releases/index.ts",
     "bcd": "tsx scripts/bulk-editor/index.ts",
+    "split": "tsx scripts/split.ts",
     "tag-web-features": "tsx scripts/tag-web-features.ts"
   }
 }

scripts/split.ts

@@ -0,0 +1,126 @@
+import { mkdir, readFile, rm, writeFile } from 'node:fs/promises';
+import { join, relative, resolve, sep } from 'node:path';
+
+import yargs from 'yargs';
+import { hideBin } from 'yargs/helpers';
+
+import { Identifier } from '../types/types';
+
+const argv = yargs(hideBin(process.argv))
+  .command('$0 [files..]', 'Split BCD JSON files', (yargs) => {
+    yargs.positional('files', {
+      describe: 'One or more JSON files to split',
+      type: 'string',
+    });
+  })
+  .help().argv as any as { files: string[] };
+
+/**
+ * Extracts the base key path (as array of strings) from a JSON file path.
+ *
+ * For example, `api/AbortController.json` becomes `['api', 'AbortController']`.
+ * @param filePath - The path to the BCD JSON file
+ * @returns Array of path components without the `.json` extension
+ */
+const getBaseKeyFromPath = (filePath: string): string[] => {
+  const relativePath = filePath.replace(/\.json$/, '').split(sep);
+  return relativePath;
+};
+
+/**
+ * Creates the JSON for the subfeature.
+ * @param baseKeys - The parent keys in which to nest the data.
+ * @param key - The key of the subfeature.
+ * @param value - The value of the subfeature.
+ * @returns JSON for the subfeature data nested in parent structure.
+ */
+const createSubfeatureJSON = (
+  baseKeys: string[],
+  key: string,
+  value: Identifier,
+) => {
+  const data = {};
+  let current = data;
+
+  for (const baseKey of baseKeys) {
+    current[baseKey] = {};
+    current = current[baseKey];
+  }
+
+  current[key] = {
+    __compat: value.__compat,
+  };
+
+  return data;
+};
+
+/**
+ * Checks if data contains compat data.
+ * @param data - The data to check for `__compat` entries.
+ * @returns TRUE, if the data contains any compat data.
+ */
+const hasCompatData = (data: any) =>
+  '__compat' in data ||
+  (typeof data === 'object' && Object.values(data).some(hasCompatData));
+
+/**
+ * Writes a JSON file.
+ * @param path - The path to the file.
+ * @param data - The data to write as JSON.
+ * @returns Promise.
+ */
+const writeJSONFile = async (path: string, data: Identifier) =>
+  writeFile(path, JSON.stringify(data, null, 2) + '\n');
+
+/**
+ * Splits a BCD-style JSON file into separate files for each subfeature.
+ * Each file will include only the `__compat` data of a given property.
+ * Extracted entries are also removed from the original file.
+ * @param file - The absolute or relative path to the source JSON file
+ */
+const splitFile = async (file: string) => {
+  const fullPath = resolve(file);
+  const raw = await readFile(fullPath, 'utf-8');
+  const data = JSON.parse(raw) as Identifier;
+
+  const baseKeys = getBaseKeyFromPath(file);
+  let current = data;
+
+  for (const key of baseKeys) {
+    if (!(key in current)) {
+      console.error(`❌ Error: Key "${key}" not found in structure.`);
+      return;
+    }
+    current = current[key];
+  }
+
+  const dirPath = fullPath.replace(/\.json$/, '');
+
+  // Write file for each subfeature, then remove subfeature from parent file.
+  for (const [key, value] of Object.entries(current)) {
+    if (key === '__compat') {
+      continue;
+    }
+    if (typeof value === 'object' && '__compat' in value) {
+      const data = createSubfeatureJSON(baseKeys, key, value);
+
+      await mkdir(dirPath, { recursive: true });
+      const outFile = join(dirPath, `${key}.json`);
+      await writeJSONFile(outFile, data);
+      console.log(`✔ Created: ${relative(process.cwd(), outFile)}`);
+
+      Reflect.deleteProperty(current, key);
+    }
+  }
+
+  // Check if current file still has any data.
+  if (hasCompatData(data)) {
+    await writeJSONFile(fullPath, data);
+    console.log(`✔ Updated: ${file}`);
+  } else {
+    await rm(fullPath);
+    console.log(`✔ Deleted: ${file}`);
+  }
+};
+
+await Promise.all(argv.files.map(splitFile));