Add update-codeowners script

Right now it works but doesn't open a PR for you.
Also not present as an npm script.

scripts/tsconfig.json

@@ -2,12 +2,7 @@
     "compilerOptions": {
         "module": "commonjs",
         "target": "es6",
-        "noImplicitAny": true,
-        "strictNullChecks": true,
-        "noImplicitReturns": true,
-        "noImplicitThis": true,
-        "noUnusedLocals": true,
-        "noUnusedParameters": true,
+        "strict": true,
         "baseUrl": "../types",
         "typeRoots": [
             "../types"
@@ -15,4 +10,4 @@
         "types": [],
         "forceConsistentCasingInFileNames": true
     }
-}
+}

scripts/update-codeowners.js

@@ -0,0 +1,57 @@
+const { AllPackages, getDefinitelyTyped, logUncaughtErrors, loggerWithErrors,
+        parseDefinitions, parseNProcesses, clean } = require("types-publisher");
+const { writeFile } = require("fs-extra");
+
+logUncaughtErrors(main());
+
+async function main() {
+    const options = { definitelyTypedPath: "..", progress: false, parseInParallel: true };
+    const log = loggerWithErrors()[0];
+
+    clean();
+    const dt = await getDefinitelyTyped(options, log);
+    await parseDefinitions(dt, { nProcesses: parseNProcesses(), definitelyTypedPath: ".." }, log);
+    const allPackages = await AllPackages.read(dt);
+    const typings = allPackages.allTypings();
+    const maxPathLen = Math.max(...typings.map(t => t.subDirectoryPath.length));
+    const entries = mapDefined(typings, t => getEntry(t, maxPathLen));
+    await writeFile([options.definitelyTypedPath, ".github", "CODEOWNERS"].join("/"), `${header}\n\n${entries.join("\n")}\n`, { encoding: "utf-8" });
+}
+
+const header =
+`# This file is generated.
+# Add yourself to the "Definitions by:" list instead.
+# See https://github.com/DefinitelyTyped/DefinitelyTyped#edit-an-existing-package`;
+
+/**
+ * @param { { contributors: ReadonlyArray<{githubUsername?: string }>, subDirectoryPath: string} } pkg
+ * @param {number} maxPathLen
+ * @return {string | undefined}
+ */
+function getEntry(pkg, maxPathLen) {
+    const users = mapDefined(pkg.contributors, c => c.githubUsername);
+    if (!users.length) {
+        return undefined;
+    }
+
+    const path = `${pkg.subDirectoryPath}/`.padEnd(maxPathLen);
+    return `/types/${path} ${users.map(u => `@${u}`).join(" ")}`;
+}
+
+/**
+ * @template T,U
+ * @param {ReadonlyArray<T>} arr
+ * @param {(t: T) => U | undefined} mapper
+ * @return U[]
+ */
+function mapDefined(arr, mapper) {
+    const out = [];
+    for (const a of arr) {
+        const res = mapper(a);
+        if (res !== undefined) {
+            out.push(res);
+        }
+    }
+    return out;
+}
+