Prototype a webpack plugin that makes the output files executable

Author: miorel

workspaces/fetch-leetcode-problem-list/package.json

@@ -15,7 +15,7 @@
   "type": "module",
   "exports": "./src/main.ts",
   "scripts": {
-    "build": "cross-env NODE_OPTIONS=\"--import tsx\" webpack && chmod +x dist/fetch-leetcode-problem-list.cjs",
+    "build": "cross-env NODE_OPTIONS=\"--import tsx\" webpack",
     "format": "prettier --color --write .",
     "lint": "eslint --color --max-warnings=0 .",
     "start": "tsx src/main.ts",

workspaces/fetch-leetcode-problem-list/webpack.config.ts

@@ -1,7 +1,9 @@
+import { chmod } from "node:fs/promises";
 import { builtinModules } from "node:module";
 import path from "node:path";
 
 import webpack, {
+  type Compiler,
   type Configuration,
   type ExternalItemFunctionData,
 } from "webpack";
@@ -11,6 +13,32 @@ import { stripPrefixOrThrow } from "@code-chronicles/util/stripPrefixOrThrow";
 
 import packageJson from "./package.json" with { type: "json" };
 
+class WebpackMakeOutputExecutablePLugin {
+  // eslint-disable-next-line class-methods-use-this -- This is the interface expected by webpack.
+  apply(compiler: Compiler): void {
+    compiler.hooks.afterEmit.tapAsync("WebpackMakeOutputExecutablePLugin", async (compilation) => {
+      const promises: Promise<void>[] = [];
+
+      for (const chunk of compilation.chunks) {
+        if (!chunk.canBeInitial()) {
+          continue;
+        }
+
+        for (const file of chunk.files) {
+          promises.push(
+            chmod(
+              path.join(compilation.outputOptions.path ?? ".", file),
+              0o755,
+            ),
+          );
+        }
+      }
+
+      await Promise.all(promises);
+    });
+  }
+}
+
 const config: Configuration = {
   target: "node",
   entry: path.resolve(__dirname, packageJson.exports),
@@ -58,6 +86,8 @@ const config: Configuration = {
       raw: true,
       entryOnly: true,
     }),
+
+    new WebpackMakeOutputExecutablePLugin(),
   ],
 };
 

workspaces/util/src/only.ts

@@ -1,6 +1,22 @@
 import invariant from "invariant";
+import nullthrows from "nullthrows";
 
-export function only<T>(array: readonly T[]): T {
-  invariant(array.length === 1, "Expected a single element array!");
-  return array[0];
+export function only<T>(iterable: Iterable<T>): T {
+  if (Array.isArray(iterable)) {
+    const { length } = iterable;
+    invariant(
+      length === 1,
+      "Given array has length %d, not 1 as expected!",
+      length,
+    );
+    return iterable[0];
+  }
+
+  let elementBox: { element: T } | null = null;
+  for (const element of iterable) {
+    invariant(elementBox == null, "Iterable had multiple elements!");
+    elementBox = { element };
+  }
+
+  return nullthrows(elementBox, "Empty iterable!").element;
 }