Add TypeScript typechecking and configure for CI (#4606)

Author: hyperupcall

.github/workflows/validate.yml

@@ -15,5 +15,6 @@ jobs:
           cache: 'npm'
           cache-dependency-path: './package-lock.json'
       - run: 'npm clean-install'
+      - run: 'npm run typecheck'
       - run: 'npm run eslint'
       - run: 'node ./cli.js check'

cli.js

@@ -6,11 +6,11 @@ import fsCb from 'node:fs'
 import readline from 'node:readline'
 import util from 'node:util'
 
-import AjvDraft04 from 'ajv-draft-04'
+import _AjvDraft04 from 'ajv-draft-04'
 import { Ajv as AjvDraft06And07 } from 'ajv'
-import Ajv2019 from 'ajv/dist/2019.js'
-import Ajv2020 from 'ajv/dist/2020.js'
-import addFormats from 'ajv-formats'
+import _Ajv2019 from 'ajv/dist/2019.js'
+import _Ajv2020 from 'ajv/dist/2020.js'
+import _addFormats from 'ajv-formats'
 import { ajvFormatsDraft2019 } from '@hyperupcall/ajv-formats-draft2019'
 import schemasafe from '@exodus/schemasafe'
 import TOML from 'smol-toml'
@@ -20,12 +20,30 @@ import * as jsoncParser from 'jsonc-parser'
 import ora from 'ora'
 import chalk from 'chalk'
 import minimist from 'minimist'
-import fetch from 'node-fetch'
+import fetch, { FetchError } from 'node-fetch'
 
 /**
  * @import { Ora } from 'ora'
  */
 
+/**
+ * Ajv defines types, but they don't work when importing the library with
+ * ESM syntax. Tweaking `jsconfig.json` with `esModuleInterop` didn't seem
+ * to fix things, so manually set the types with a cast. This issue is
+ * tracked upstream at https://github.com/ajv-validator/ajv/issues/2132.
+ */
+/** @type {typeof _AjvDraft04.default} */
+const AjvDraft04 = /** @type {any} */ (_AjvDraft04)
+
+/** @type {typeof _Ajv2019.default} */
+const Ajv2019 = /** @type {any} */ (_Ajv2019)
+
+/** @type {typeof _Ajv2020.default} */
+const Ajv2020 = /** @type {any} */ (_Ajv2020)
+
+/** @type {typeof _addFormats.default} */
+const addFormats = /** @type {any} */ (_addFormats)
+
 // Declare constants.
 const AjvDraft06SchemaJson = await readJsonFile(
   'node_modules/ajv/dist/refs/json-schema-draft-06.json',
@@ -843,7 +861,9 @@ async function taskMaintenance() {
                 `NOT OK (${res.status}/${res.statusText}): ${url} (after 405 code)`,
               )
             } catch (err) {
-              console.info(`NOT OK (${err.code}): ${url} (after 405 code)`)
+              console.info(
+                `NOT OK (${/** @type {FetchError} */ (err).code}): ${url} (after 405 code)`,
+              )
             }
             return
           }

jsconfig.json

@@ -1,8 +1,9 @@
 {
+  "include": ["cli.js"],
   "compilerOptions": {
     "target": "es2022",
-    "module": "Node16",
-    "moduleResolution": "Node16",
+    "module": "node16",
+    "moduleResolution": "node16",
     "strict": true
   }
 }

package-lock.json

@@ -19,6 +19,7 @@
   "scripts": {
     "prettier": "prettier --config .prettierrc.cjs --ignore-path .gitignore --check .",
     "prettier:fix": "prettier --config .prettierrc.cjs --ignore-path .gitignore --write .",
+    "typecheck": "tsc --project ./jsconfig.json",
     "eslint": "eslint ./cli.js",
     "eslint:fix": "eslint --fix ./cli.js",
     "build": "echo \"WARNING: Please use 'node ./cli.js' instead of 'npm run'. This method for execution will be removed.\" && npm run eslint && node ./cli.js check && ./scripts/dirty_repository_check.sh"
@@ -28,6 +29,7 @@
     "@exodus/schemasafe": "^1.3.0",
     "@hyperupcall/ajv-formats-draft2019": "^1.7.2",
     "@prantlf/jsonlint": "^16.0.0",
+    "@types/node": "^22.13.11",
     "ajv": "^8.17.1",
     "ajv-draft-04": "^1.0.0",
     "ajv-formats": "^2.1.1",
@@ -45,6 +47,7 @@
     "prettier-plugin-sort-json": "^4.0.0",
     "prettier-plugin-toml": "^2.0.1",
     "smol-toml": "^1.3.1",
+    "typescript": "^5.8.2",
     "yaml": "^2.6.1"
   }
 }