Add Typescript for type checking (but still with js files)

.eslintrc.json

@@ -3,7 +3,8 @@
     "es2021": true,
     "node": true
   },
-  "extends": "standard",
+  "extends": ["eslint:recommended", "plugin:@typescript-eslint/recommended"],
+  "parser": "@typescript-eslint/parser",
   "parserOptions": {
     "ecmaVersion": "latest",
     "sourceType": "module"

.gitignore

@@ -1,3 +1,4 @@
 /node_modules
+/@types
 npm-debug.log
 .DS_Store

index.d.ts

@@ -0,0 +1,54 @@
+import { Transform } from "readable-stream";
+
+import {Buffer} from "safe-buffer";
+
+export declare module 'encoding' {
+    export function convert(buf: Buffer, toCharset: string, fromCharset: string): Buffer;
+}
+
+export interface Compiler {
+    _table: GetTextTranslations;
+    compile(): Buffer;
+}
+
+export interface GetTextComment {
+    translator?: string;
+    reference?: string;
+    extracted?: string;
+    flag?: string;
+    previous?: string;
+}
+
+export interface GetTextTranslation {
+    msgctxt?: string;
+    msgid: string;
+    msgid_plural?: string;
+    msgstr: string[];
+    comments?: GetTextComment;
+}
+
+export interface GetTextTranslations {
+    charset: string;
+    headers: { [headerName: string]: string };
+    translations: { [msgctxt: string]: { [msgId: string]: GetTextTranslation } };
+}
+
+export interface parserOptions {
+    defaultCharset?: string;
+    validation?: boolean;
+}
+
+export interface po {
+    parse: (buffer: Buffer | string, defaultCharset?: string) => GetTextTranslations;
+    compile: (table: GetTextTranslations, options?: parserOptions) => Buffer;
+    createParseStream: (options?: parserOptions, transformOptions?: import('readable-stream').TransformOptions) => Transform;
+}
+
+export interface mo {
+    parse: (buffer: Buffer | string, defaultCharset?: string) => GetTextTranslations;
+    compile: (table: GetTextTranslations, options?: parserOptions) => Buffer;
+}
+
+export * from "./@types";
+
+export default { po, mo } as { po: po, mo: mo };

index.js

@@ -3,12 +3,24 @@ import poCompiler from './lib/pocompiler.js';
 import moParser from './lib/moparser.js';
 import moCompiler from './lib/mocompiler.js';
 
+/**
+ * Translation parser and compiler for PO files
+ * @see https://www.gnu.org/software/gettext/manual/html_node/PO.html
+ *
+ * @type {import("./index.d.ts").po} po
+ */
 export const po = {
   parse: poParser.parse,
   createParseStream: poParser.stream,
   compile: poCompiler
 };
 
+/**
+ * Translation parser and compiler for PO files
+ * @see https://www.gnu.org/software/gettext/manual/html_node/MO.html
+ *
+ * @type {import("./index.d.ts").mo} mo
+ */
 export const mo = {
   parse: moParser,
   compile: moCompiler

lib/mocompiler.js

@@ -7,20 +7,21 @@ import contentType from 'content-type';
  * Exposes general compiler function. Takes a translation
  * object as a parameter and returns binary MO object
  *
- * @param {Object} table Translation object
+ * @param {import('./index.d.ts').GetTextTranslations} table Translation object
  * @return {Buffer} Compiled binary MO object
  */
 export default function (table) {
   const compiler = new Compiler(table);
 
   return compiler.compile();
-};
+}
 
 /**
  * Creates a MO compiler object.
  *
  * @constructor
- * @param {Object} table Translation table as defined in the README
+ * @param {import('./index.d.ts').GetTextTranslations} table Translation table as defined in the README
+ * @return {import('./index.d.ts').Compiler} Compiler
  */
 function Compiler (table = {}) {
   this._table = table;
@@ -148,7 +149,7 @@ Compiler.prototype._generateList = function () {
 /**
  * Calculate buffer size for the final binary object
  *
- * @param {Array} list An array of translation strings from _generateList
+ * @param {import('./index.d.ts').GetTextTranslations} list An array of translation strings from _generateList
  * @return {Object} Size data of {msgid, msgstr, total}
  */
 Compiler.prototype._calculateSize = function (list) {
@@ -183,7 +184,7 @@ Compiler.prototype._calculateSize = function (list) {
 /**
  * Generates the binary MO object from the translation list
  *
- * @param {Array} list translation list
+ * @param {import('./index.d.ts').GetTextTranslations} list translation list
  * @param {Object} size Byte size information
  * @return {Buffer} Compiled MO object
  */

lib/moparser.js

@@ -12,7 +12,7 @@ export default function (buffer, defaultCharset) {
   const parser = new Parser(buffer, defaultCharset);
 
   return parser.parse();
-};
+}
 
 /**
  * Creates a MO parser object.

lib/pocompiler.js

@@ -14,7 +14,7 @@ export default function (table, options) {
   const compiler = new Compiler(table, options);
 
   return compiler.compile();
-};
+}
 
 /**
  * Creates a PO compiler object.

lib/poparser.js

@@ -14,18 +14,18 @@ export function parse (input, options = {}) {
   const parser = new Parser(input, options);
 
   return parser.parse();
-};
+}
 
 /**
  * Parses a PO stream, emits translation table in object mode
  *
- * @typedef {{ defaultCharset: strubg, validation: boolean }} Options
+ * @typedef {{ defaultCharset: string, validation: boolean }} Options
  * @param {Options} [options] Optional options with defaultCharset and validation
  * @param {import('readable-stream').TransformOptions} [transformOptions] Optional stream options
  */
 export function stream (options = {}, transformOptions = {}) {
   return new PoParserTransform(options, transformOptions);
-};
+}
 
 /**
  * Creates a PO parser object. If PO object is a string,
@@ -515,7 +515,7 @@ Parser.prototype._finalize = function (tokens) {
 /**
  * Creates a transform stream for parsing PO input
  *
- * @typedef {{ defaultCharset: strubg, validation: boolean }} Options
+ * @typedef {{ defaultCharset: string, validation: boolean }} Options
  * @constructor
  * @param {Options} options Optional options with defaultCharset and validation
  * @param {import('readable-stream').TransformOptions} transformOptions Optional stream options

lib/shared.js

@@ -45,8 +45,8 @@ export function parseHeader (str = '') {
  * @param {Object} [headers = {}] An object with parsed headers
  * @returns {number} Parsed result
  */
-export function parseNPluralFromHeadersSafely (headers = {}, fallback = 1) {
-  const pluralForms = headers[PLURAL_FORMS];
+export function parseNPluralFromHeadersSafely (headers, fallback = 1) {
+  const pluralForms = headers ? headers[PLURAL_FORMS] : false;
 
   if (!pluralForms) {
     return fallback;
@@ -101,7 +101,7 @@ export function formatCharset (charset = 'iso-8859-1', defaultCharset = 'iso-885
  *
  * @param {String} str PO formatted string to be folded
  * @param {Number} [maxLen=76] Maximum allowed length for folded lines
- * @return {Array} An array of lines
+ * @return {string[]} An array of lines
  */
 export function foldLine (str, maxLen = 76) {
   const lines = [];

package.json

@@ -22,9 +22,11 @@
     "test-generate-mo": "msgfmt test/fixtures/latin13.po -o test/fixtures/latin13.mo & msgfmt test/fixtures/utf8.po -o test/fixtures/utf8.mo & msgfmt test/fixtures/obsolete.po -o test/fixtures/obsolete.mo",
     "test": "mocha",
     "preversion": "npm run lint && npm test",
-    "postversion": "git push && git push --tags"
+    "postversion": "git push && git push --tags",
+    "prepublish": "tsc && npm run lint && npm run test"
   },
   "main": "./index.js",
+  "types": "./index.d.ts",
   "license": "MIT",
   "dependencies": {
     "content-type": "^1.0.5",
@@ -33,13 +35,20 @@
     "safe-buffer": "^5.2.1"
   },
   "devDependencies": {
+    "@types/chai": "latest",
+    "@types/content-type": "^1.1.8",
+    "@types/mocha": "latest",
+    "@types/readable-stream": "^4.0.11",
+    "@typescript-eslint/eslint-plugin": "^6.18.1",
+    "@typescript-eslint/parser": "^6.14.0",
     "chai": "^5.0.3",
     "eslint": "^8.56.0",
     "eslint-config-standard": "^17.1.0",
     "eslint-plugin-import": "^2.29.1",
     "eslint-plugin-n": "^16.6.2",
     "eslint-plugin-promise": "^6.1.1",
-    "mocha": "^10.3.0"
+    "mocha": "^10.3.0",
+    "typescript": "^5.4.4"
   },
   "keywords": [
     "i18n",

tsconfig.json

@@ -0,0 +1,36 @@
+{
+  "compilerOptions": {
+    "noImplicitAny": true,
+    "removeComments": false,
+    "module": "Node16",
+    "moduleResolution": "Node16",
+    "target": "ES2015",
+
+    // Strict mode
+    "strict": true,
+
+    // Allow javascript files
+    "allowJs": true,
+
+    // Check js files for errors
+    "checkJs": false,
+
+    // Output d.ts files to @types
+    "outDir": "@types",
+
+    // Generate d.ts files
+    "declaration": true,
+
+    // This compiler run should
+    // only output d.ts files
+    "emitDeclarationOnly": true,
+    // Minify
+    "pretty": false,
+    // Skip lib check when compiling
+    "skipLibCheck": true
+  },
+  "include": [
+    "lib/**/*.js",
+    "index.d.ts"
+  ]
+}