Add a script to list unmapped compat keys

Author: ddbeck

scripts/unmapped-compat-keys.ts

@@ -0,0 +1,116 @@
+import { Temporal } from "@js-temporal/polyfill";
+import { coreBrowserSet } from "compute-baseline";
+import { Compat, Feature } from "compute-baseline/browser-compat-data";
+import winston from "winston";
+import yargs from "yargs";
+import { features } from "../index.js";
+import { support } from "../packages/compute-baseline/dist/baseline/support.js";
+import { isOrdinaryFeatureData } from "../type-guards.js";
+
+const compat = new Compat();
+const browsers = coreBrowserSet.map((b) => compat.browser(b));
+const today = Temporal.Now.plainDateISO();
+
+const argv = yargs(process.argv.slice(2))
+  .scriptName("unmapped-compat-keys")
+  .usage(
+    "$0",
+    "Print keys from mdn/browser-compat-data not assigned to a feature",
+  )
+  .option("format", {
+    choices: ["json", "yaml"],
+    default: "yaml",
+    describe:
+      "Choose the output format. JSON has more detail, while YAML is suited to pasting into feature files.",
+  })
+  .option("verbose", {
+    alias: "v",
+    describe: "Show more information",
+    type: "count",
+    default: 0,
+    defaultDescription: "warn",
+  }).argv;
+
+const logger = winston.createLogger({
+  level: argv.verbose > 0 ? "debug" : "warn",
+  format: winston.format.combine(
+    winston.format.colorize(),
+    winston.format.simple(),
+  ),
+  transports: new winston.transports.Console(),
+});
+
+const mappedCompatKeys = (() => {
+  return new Set(
+    Object.values(features).flatMap((f) => {
+      if (isOrdinaryFeatureData(f)) {
+        return f.compat_features ?? [];
+      }
+      return [];
+    }),
+  );
+})();
+
+const compatFeatures: Map<Feature, number> = (() => {
+  const map = new Map();
+  for (const f of compat.walk()) {
+    if (f.id.startsWith("webextensions")) {
+      continue;
+    }
+    if (mappedCompatKeys.has(f.id)) {
+      logger.debug(`${f.id} skipped, already mapped to a feature`);
+      continue;
+    }
+
+    map.set(f, cumulativeDaysShipped(f));
+  }
+  return map;
+})();
+
+const byAge = [...compatFeatures.entries()].sort(
+  ([aFeature, aDays], [bFeature, bDays]) => aDays - bDays,
+);
+
+if (argv.format === "yaml") {
+  for (const [f, days] of byAge) {
+    console.log(`  - ${f.id}`);
+  }
+}
+
+if (argv.format === "json") {
+  console.log(
+    JSON.stringify(
+      byAge.map(([f, days]) => ({
+        key: f.id,
+        cumulativeDaysShipped: days,
+        deprecated: f.deprecated,
+      })),
+      undefined,
+      2,
+    ),
+  );
+}
+
+/**
+ * Returns the sum of days that this compat key has been shipping in each
+ * browser in the Baseline core browser set.
+ *
+ * Like the Baseline calculation, this excludes features that are partially
+ * implemented, prefixed, behind flags, or in not-yet-stable releases.
+ *
+ * @param {Feature} feature a compat feature object
+ * @return {number} an integer
+ */
+function cumulativeDaysShipped(feature: Feature) {
+  const results = support(feature, browsers);
+  return [...results.values()]
+    .filter((r) => r !== undefined)
+    .map(
+      (r) =>
+        r.release.date.until(today, {
+          largestUnit: "days",
+          smallestUnit: "days",
+        }).days,
+    )
+    .reduce((prev, curr) => prev + curr, 0);
+}