diff --git a/cjs/index.js b/cjs/index.js
index 2b2d1c2..0877a5f 100644
--- a/cjs/index.js
+++ b/cjs/index.js
@@ -32,7 +32,10 @@ let detector;
     const isPromise = (o) => typeof o.then === "function";
     let cacheLocal = "";
     /**
-     * @type {NsOsLocale.TInternalLocaleDetectorSig}
+     * @template {true | void} IsAsync
+     * @template {Conditional<IsAsync, string, Promise<string>>} R
+     * @param {IsAsync=} async
+     * @returns {(options?: NsOsLocale.LocaleDetectorOptions) => R}
      */
     const detectorBase = (async) => (options = {}) => {
         /* eslint-disable indent */
@@ -42,7 +45,7 @@ let detector;
             return (async ? Promise.resolve(cacheLocal) : cacheLocal);
         }
         const functions = localeGetters[+(!!async)];
-        /** @type {NsOsLocale.TInternalLocaleDetectorResult} */
+        /** @type {R} */
         let locale;
         /**
          * @param {string} l
@@ -52,18 +55,18 @@ let detector;
         const withCache = (l, mustPromise) => {
             l = l.replace(/_/, "-");
             cacheLocal = cache ? l : "";
-            return (mustPromise ? Promise.resolve(l) : l);
+            return /** @type {NsOsLocale.TInternalLocaleDetectorResult} */ (mustPromise ? Promise.resolve(l) : l);
         };
         const envLocale = getEnvLocale();
         if (envLocale || !options.spawn) {
-            locale = purgeExtraToken(envLocale);
+            locale = /** @type {R} */ (purgeExtraToken(envLocale));
         }
         else {
             let { platform } = process;
             if (platform !== "win32" && platform !== "darwin") {
                 platform = "linux";
             }
-            locale = functions[platform]();
+            locale = /** @type {R} */ (functions[platform]());
         }
         return (isPromise(locale) ? locale.then(withCache) : withCache(locale, async === true || void 0));
     };
@@ -77,7 +80,7 @@ let detector;
             enumerable: false,
         },
         version: {
-            value: "v1.0.19",
+            value: "v1.0.20",
             enumerable: true,
         },
     });
diff --git a/cjs/lib.js b/cjs/lib.js
index 47fbc9d..09318ac 100644
--- a/cjs/lib.js
+++ b/cjs/lib.js
@@ -181,8 +181,8 @@ const [getUnixLocale, getUnixLocaleSync] = /** @type {(cmd: TLocalCmdToken) => T
  * @see {@link module:lcid}
  */
 const parseLCID = (result) => {
-    const lcidCode = parseInt(result.replace("Locale", ""), 16);
-    return lcid.from(lcidCode) || defaultLocale;
+    const lcidCode = +("0x" + result.replace(/Locale|\s/g, ""));
+    return lcid.from(lcidCode) || /* istanbul ignore next */ defaultLocale;
 };
 const [getWinLocale, getWinLocaleSync] = /** @type {(a: TLocalCmdToken, b: string[]) => TAsyncSyncPair} */ ((command, args) => {
     return [
diff --git a/esm/index.js b/esm/index.mjs
similarity index 82%
rename from esm/index.js
rename to esm/index.mjs
index 5bb7c95..7fdba08 100644
--- a/esm/index.js
+++ b/esm/index.mjs
@@ -14,7 +14,7 @@
 // @ts-ignore
 ///<reference path="../index.d.ts"/>
 ///<reference types="basic-types"/>
-import * as lib from "./lib";
+import * as lib from "./lib.mjs";
 /**
  * @typedef {(o: any) => o is Promise<any>} TPromiseChecker
  */
@@ -29,7 +29,10 @@ let detector;
     const isPromise = (o) => typeof o.then === "function";
     let cacheLocal = "";
     /**
-     * @type {NsOsLocale.TInternalLocaleDetectorSig}
+     * @template {true | void} IsAsync
+     * @template {Conditional<IsAsync, string, Promise<string>>} R
+     * @param {IsAsync=} async
+     * @returns {(options?: NsOsLocale.LocaleDetectorOptions) => R}
      */
     const detectorBase = (async) => (options = {}) => {
         /* eslint-disable indent */
@@ -39,7 +42,7 @@ let detector;
             return (async ? Promise.resolve(cacheLocal) : cacheLocal);
         }
         const functions = localeGetters[+(!!async)];
-        /** @type {NsOsLocale.TInternalLocaleDetectorResult} */
+        /** @type {R} */
         let locale;
         /**
          * @param {string} l
@@ -49,18 +52,18 @@ let detector;
         const withCache = (l, mustPromise) => {
             l = l.replace(/_/, "-");
             cacheLocal = cache ? l : "";
-            return (mustPromise ? Promise.resolve(l) : l);
+            return /** @type {NsOsLocale.TInternalLocaleDetectorResult} */ (mustPromise ? Promise.resolve(l) : l);
         };
         const envLocale = getEnvLocale();
         if (envLocale || !options.spawn) {
-            locale = purgeExtraToken(envLocale);
+            locale = /** @type {R} */ (purgeExtraToken(envLocale));
         }
         else {
             let { platform } = process;
             if (platform !== "win32" && platform !== "darwin") {
                 platform = "linux";
             }
-            locale = functions[platform]();
+            locale = /** @type {R} */ (functions[platform]());
         }
         return (isPromise(locale) ? locale.then(withCache) : withCache(locale, async === true || void 0));
     };
@@ -74,7 +77,7 @@ let detector;
             enumerable: false,
         },
         version: {
-            value: "v1.0.19",
+            value: "v1.0.20",
             enumerable: true,
         },
     });
diff --git a/esm/lib.js b/esm/lib.mjs
similarity index 97%
rename from esm/lib.js
rename to esm/lib.mjs
index 8feb91f..23e88a2 100644
--- a/esm/lib.js
+++ b/esm/lib.mjs
@@ -178,8 +178,8 @@ const [getUnixLocale, getUnixLocaleSync] = /** @type {(cmd: TLocalCmdToken) => T
  * @see {@link module:lcid}
  */
 const parseLCID = (result) => {
-    const lcidCode = parseInt(result.replace("Locale", ""), 16);
-    return lcid.from(lcidCode) || defaultLocale;
+    const lcidCode = +("0x" + result.replace(/Locale|\s/g, ""));
+    return lcid.from(lcidCode) || /* istanbul ignore next */ defaultLocale;
 };
 const [getWinLocale, getWinLocaleSync] = /** @type {(a: TLocalCmdToken, b: string[]) => TAsyncSyncPair} */ ((command, args) => {
     return [
diff --git a/package.json b/package.json
index eba0294..17fbe90 100644
--- a/package.json
+++ b/package.json
@@ -1,10 +1,10 @@
 {
   "name": "os-locale-s",
-  "version": "1.0.19",
+  "version": "1.0.20",
   "description": "Its a light weight version that minimizes the dependency module of `os-locale`",
   "private": false,
   "main": "./cjs/index.js",
-  "module": "./esm/index.js",
+  "module": "./esm/index.mjs",
   "types": "./index.d.ts",
   "sideEffects": false,
   "author": {
@@ -51,6 +51,7 @@
     "lcid": "^4.0.1"
   },
   "devDependencies": {
+    "@types/node": "^20.10.6",
     "jest": "29.7.0"
   },
   "scripts": {
diff --git a/test.js b/test.js
index c27c3df..afd1bcd 100644
--- a/test.js
+++ b/test.js
@@ -1,116 +1,171 @@
-"use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
-const ifDefined = (varName, fallback) => typeof global[varName] !== "undefined" ? global[varName] : fallback;
-const debug = ifDefined("printSync", false);
-const asyncDebug = ifDefined("printAsync", false);
-const DEFAULT = 1;
-const WIN = 1;
-const LINUX = 1;
-const DARWIN = 1;
-const reLocale = /^(?:[a-z]{2}-[A-Z]{2}|C|POSIX)$/;
-const cache = {};
-const setPlatform = (platform) => {
-    Object.defineProperty(process, "platform", { value: platform });
-};
-const emitPlatformSetter = (platform, altProcess) => () => {
-    return new Promise(resolve => {
-        if (typeof altProcess === "function")
-            altProcess();
-        setPlatform(platform);
-        osLocale.purge();
-        resolve();
-    });
-};
-const isBool = (b) => typeof b === "boolean";
-function makeOption(bools) {
-    const opt = {};
-    const [spawn, cache] = bools || [];
-    isBool(spawn) && (opt.spawn = spawn);
-    isBool(cache) && (opt.cache = cache);
-    return (isBool(spawn) || isBool(cache)) ? opt : void 0;
-}
-let osLocale;
-const tryMatch = (lc) => {
-    try {
-        expect(lc).toMatch(reLocale);
-    }
-    catch (e) {
-        console.warn("There are no locales available in this environment.");
-    }
-};
-const asyncCallbackEmitter = (plat, bools) => async () => {
-    const opt = makeOption(bools);
-    const locale = await osLocale(opt);
-    asyncDebug && console.log(`async [${plat}]: ${locale}`);
-    tryMatch(locale);
-};
-const syncCallbackEmitter = (plat, bools) => () => {
-    const opt = makeOption(bools);
-    const locale = osLocale.sync(opt);
-    debug && console.log(`[${plat}]: ${locale}`);
-    tryMatch(locale);
-};
-beforeAll(async () => {
-    return new Promise(resolve => {
-        cache.env = process.env;
-        cache.platform = process.platform;
-        resolve();
-    });
-});
-// eachModule("../src/");
-eachModule("./");
-function eachModule(path) {
-    describe(`[os-locale-s], module - "${path}"`, function () {
-        beforeAll(() => {
-            process.env = {};
-            return new Promise(resolve => {
-                Promise.resolve().then(() => require(path)).then((m) => {
-                    ({ osLocale } = m);
-                    resolve();
-                });
-            });
-        });
-        describe.each([
-            ["linux", LINUX], ["win32", WIN], ["darwin", DARWIN]
-        ])("Platform: %s (process.env.platform)", (name, enable) => {
-            if (enable) {
-                beforeEach(emitPlatformSetter(name));
-                describe("locale detection with default options", function () {
-                    it("async detection", asyncCallbackEmitter(name));
-                    it("sync detection", syncCallbackEmitter(name));
-                });
-                describe("locale detection with default options (no spawn)", function () {
-                    it("async detection", asyncCallbackEmitter(name, [false]));
-                    it("sync detection", syncCallbackEmitter(name, [false]));
-                });
-                describe("locale detection with default options (no cache)", function () {
-                    it("async detection", asyncCallbackEmitter(name, [true, false]));
-                    it("sync detection", syncCallbackEmitter(name, [true, false]));
-                });
-                describe("locale detection with no spawn, no cache", function () {
-                    it("async detection", asyncCallbackEmitter(name, [false, false]));
-                    it("sync detection", syncCallbackEmitter(name, [false, false]));
-                });
-            }
-        });
-        DEFAULT && describe("OS: default (**Test depending on the actual platform)", () => {
-            beforeAll(emitPlatformSetter(cache.platform, () => process.env = cache.env));
-            describe("locale detection with default options", function () {
-                it("async detection", asyncCallbackEmitter("default"));
-                it("sync detection", syncCallbackEmitter("default"));
-            });
-            describe("locale detection with default options (no spawn)", function () {
-                it("async detection", asyncCallbackEmitter("default", [false]));
-                it("sync detection", syncCallbackEmitter("default", [false]));
-            });
-            describe("locale detection with default options (no cache)", function () {
-                it("async detection", asyncCallbackEmitter("default", [true, false]));
-                it("sync detection", syncCallbackEmitter("default", [true, false]));
-            });
-            describe("locale detection with no spawn, no cache", function () {
-                it("async detection", asyncCallbackEmitter("default", [false, false]));
-                it("sync detection", syncCallbackEmitter("default", [false, false]));
-            });
-        });
-    });
-}
+"use strict";
+/*!
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  Copyright (C) 2020 jeffy-g <hirotom1107@gmail.com>
+  Released under the MIT license
+  https://opensource.org/licenses/mit-license.php
+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+*/
+// @ts-ignore 
+/// <reference path="./index.d.ts"/>
+// @ts-ignore 
+/// <reference path="../src/index.d.ts"/>
+/**
+ * @typedef {typeof process.platform} TOSTokens
+ * @typedef {keyof typeof global} TGThisKeys
+ * @typedef {[spawn?: boolean, cache?: boolean]} TDetectorOptValues
+ * @typedef TProcessCache
+ * @prop {typeof process["env"]} env
+ * @prop {TOSTokens} platform
+ */
+/**
+ * @template {*} T
+ * @typedef {{-readonly [P in keyof T]: T[P]}} XReadonly
+ */
+/**
+ * @typedef LocaleDetectorOptions
+ * @prop {boolean} [spawn] Set to `false` to avoid spawning subprocesses and instead only resolve the locale from environment variables.&#64;default true
+ * @prop {boolean} [cache] &#64;default true
+ */
+/**
+ * @type {NsOsLocale.LocaleDetector}
+ */
+let osLocale;
+// @ts-ignore 
+const ifDefined = (varName, fallback) => typeof global[varName] !== "undefined" ? global[varName] : fallback;
+const debug = ifDefined("printSync", false);
+const asyncDebug = ifDefined("printAsync", false);
+const DEFAULT = 1;
+const WIN = 1;
+const LINUX = 1;
+const DARWIN = 1;
+const reLocale = /^(?:[a-z]{2}-[A-Z]{2}|C|POSIX)$/;
+/** @type {TProcessCache} */
+const cache = {
+    env: process.env,
+    platform: process.platform
+};
+/**
+ *
+ * @param {TOSTokens} platform "darwin", "linux", "win32"
+ */
+const setPlatform = (platform) => {
+    Object.defineProperty(process, "platform", { value: platform });
+};
+/**
+ * @param {TOSTokens} platform
+ * @param {() => void} [extraProcess]
+ * @returns {() => Promise<void>}
+ */
+const setPlatformOf = (platform, extraProcess) => () => {
+    return new Promise(resolve => {
+        extraProcess && extraProcess();
+        setPlatform(platform);
+        // @ts-ignore @internal
+        osLocale.purge();
+        resolve();
+    });
+};
+/**
+ * @param {boolean=} b
+ * @returns {b is boolean}
+ */
+const isBool = (b) => typeof b === "boolean";
+/**
+ * @param {TDetectorOptValues=} bools
+ * @returns
+ */
+function makeOption(bools) {
+    /** @type {XReadonly<LocaleDetectorOptions>} */
+    const opt = {};
+    const [spawn, cache] = bools || [];
+    isBool(spawn) && (opt.spawn = spawn);
+    isBool(cache) && (opt.cache = cache);
+    return (isBool(spawn) || isBool(cache)) ? opt : void 0;
+}
+const tryMatch = (lc) => {
+    try {
+        expect(lc).toMatch(reLocale);
+    }
+    catch (e) {
+        console.warn("There are no locales available in this environment.");
+    }
+};
+/**
+ * @param {string} prefix
+ * @param {string} locale
+ * @param {XReadonly<LocaleDetectorOptions>=} opt
+ */
+const printInfo = (prefix, locale, opt) => console.log(`${prefix}[platform: ${process.platform}, options: ${opt ? JSON.stringify(opt) : "use default(undefined)"}]: ${locale}`);
+/**
+ * @param {TDetectorOptValues=} detectorOpt [spawn, cache]
+ * @param {true=} async
+ */
+const emitCallback = (detectorOpt, async) => async () => {
+    const opt = makeOption(detectorOpt);
+    const fn = async ? osLocale : osLocale.sync;
+    const result = fn(opt);
+    const locale = /** @type {string} */ (async ? await result : result);
+    debug && printInfo(async ? "async " : "", locale, opt);
+    tryMatch(locale);
+};
+
+eachModule(".");
+/**
+ * @param {string} path module path `"../src/"(.ts)` or `"../dist/"(.js)`
+ */
+function eachModule(path) {
+    describe(` ====================== running test: [os-locale-s], module - "${path}" ======================`, function () {
+        beforeAll(/** @type {() => Promise<void>} */ () => {
+            process.env = {};
+            return new Promise(resolve => {
+                Promise.resolve(`${path}`).then(s => require(s)).then((m) => {
+                    ({ osLocale } = m);
+                    resolve();
+                });
+            });
+        });
+        describe.each([
+            [/** @type {TOSTokens} */ ("linux"), LINUX], [/** @type {TOSTokens} */ ("win32"), WIN], [/** @type {TOSTokens} */ ("darwin"), DARWIN]
+        ])("[[[ Platform: %s (process.env.platform) ]]]", (name, enable) => {
+            if (enable) {
+                beforeEach(setPlatformOf(name));
+                describe("locale detection with default options", function () {
+                    it("async detection", emitCallback(void 0, true));
+                    it("sync detection", emitCallback());
+                });
+                describe("locale detection with default options (no spawn)", function () {
+                    it("async detection", emitCallback([false], true));
+                    it("sync detection", emitCallback([false]));
+                });
+                describe("locale detection with default options (no cache)", function () {
+                    it("async detection", emitCallback([true, false], true));
+                    it("sync detection", emitCallback([true, false]));
+                });
+                describe("locale detection with no spawn, no cache", function () {
+                    it("async detection", emitCallback([false, false], true));
+                    it("sync detection", emitCallback([false, false]));
+                });
+            }
+        });
+        DEFAULT && describe("[[[ OS: default (**Test depending on the actual platform) ]]]", () => {
+            beforeAll(setPlatformOf(cache.platform, () => process.env = cache.env));
+            describe("locale detection with default options", function () {
+                it("async detection", emitCallback(void 0, true));
+                it("sync detection", emitCallback());
+            });
+            describe("locale detection with default options (no spawn)", function () {
+                it("async detection", emitCallback([false], true));
+                it("sync detection", emitCallback([false]));
+            });
+            describe("locale detection with default options (no cache)", function () {
+                it("async detection", emitCallback([true, false], true));
+                it("sync detection", emitCallback([true, false]));
+            });
+            describe("locale detection with no spawn, no cache", function () {
+                it("async detection", emitCallback([false, false], true));
+                it("sync detection", emitCallback([false, false]));
+            });
+        });
+    });
+}
\ No newline at end of file