feat: Generate types based on javascript source

Closes #16
Replaces #17

Author: bfanger

.gitignore

@@ -2,4 +2,5 @@
 /yarn.lock
 /package-lock.json
 /pnpm-lock.yaml
-/bun.lockb
+/bun.lockb
+/types

package.json

@@ -1,6 +1,6 @@
 {
   "name": "eslint-plugin-only-warn",
-  "version": "1.1.0",
+  "version": "1.2.0",
   "license": "MIT",
   "description": "Downgrade errors to warnings",
   "keywords": [
@@ -16,17 +16,22 @@
   },
   "type": "commonjs",
   "main": "src/only-warn.js",
+  "types": "types/only-warn.d.ts",
   "prettier": {},
   "scripts": {
-    "lint": "prettier --check . && eslint .",
+    "lint": "prettier --check . && eslint . && tsc",
     "format": "eslint --fix . && prettier --write .",
     "test": "vitest run",
-    "test:watch": "vitest"
+    "test:watch": "vitest",
+    "prepublish": "rm -rf types && tsc"
   },
   "devDependencies": {
-    "eslint": "^9.4.0",
-    "eslint-config-prettier": "^9.1.0",
-    "prettier": "^3.2.5",
-    "vitest": "^1.6.0"
+    "@eslint/js": "^10.0.1",
+    "@types/node": "^25.3.2",
+    "eslint": "^10.0.2",
+    "eslint-config-prettier": "^10.1.8",
+    "prettier": "^3.8.1",
+    "typescript": "^5.9.3",
+    "vitest": "^4.0.18"
   }
 }

src/get-eslint-modules.js

@@ -1,8 +1,10 @@
+// @ts-check
 const path = require("path");
 
 const SEARCH_STR = `${path.sep}node_modules${path.sep}eslint${path.sep}`;
 
 module.exports = function getEslintModules() {
+  /** @type {Record<string, any>} */
   const map = {};
   Object.keys(require.cache).forEach((modulePath) => {
     const pos = modulePath.indexOf(SEARCH_STR);

src/only-warn.js

@@ -1,16 +1,19 @@
+// @ts-check
 const getEslintModules = require("./get-eslint-modules");
 
 const unpatchedVerify = Symbol("verify");
 
 /**
  * Patch the verify method and downgrade the errors to warnings.
+ * @param {Record<string | symbol, any>} LinterPrototype
  */
 function patch(LinterPrototype) {
   if (LinterPrototype[unpatchedVerify]) {
     return;
   }
   LinterPrototype[unpatchedVerify] = LinterPrototype.verify;
   LinterPrototype.verify = function () {
+    /** @type ReturnType<import("eslint").Linter["verify"]> */
     const messages = LinterPrototype[unpatchedVerify].apply(this, arguments);
     messages.forEach((message) => {
       if (!message.fatal && message.severity === 2) {
@@ -23,6 +26,7 @@ function patch(LinterPrototype) {
 
 /**
  * Remove the patch
+ * @param {Record<string | symbol, any>} LinterPrototype
  */
 function unpatch(LinterPrototype) {
   if (LinterPrototype[unpatchedVerify]) {

tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "module": "nodenext",
+    "target": "esnext",
+    "declaration": true,
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "allowJs": true,
+    "emitDeclarationOnly": true,
+    "outDir": "./types"
+  },
+  "include": ["./src"]
+}