feat!: implement the first idea

.babelrc.js

@@ -0,0 +1,7 @@
+module.exports = {
+  presets: [
+    [
+      "@babel/preset-env",
+    ],
+  ],
+};

.circleci/config.yml

@@ -0,0 +1,20 @@
+version: 2.1
+
+orbs:
+  node: circleci/[email protected]
+
+jobs:
+  build-and-test:
+    docker:
+      - image: cimg/node:15.1
+    steps:
+      - checkout
+      - node/install-packages
+      - run:
+          name: Run tests
+          command: npm test
+
+workflows:
+  run-test:
+    jobs:
+      - build-and-test

.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

.eslintrc.js

@@ -0,0 +1,21 @@
+module.exports = {
+  "env": {
+    "browser": true,
+    "es2021": true,
+    "node": true
+  },
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended"
+  ],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": "latest",
+    "sourceType": "module"
+  },
+  "plugins": [
+    "@typescript-eslint"
+  ],
+  "rules": {
+  }
+}

.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+node_modules
+dist
+yarn-error.log

README.md

@@ -1 +1,26 @@
-# mb_strwidth
+# mb_strwidth
+
+mb_strwidth ported to JavaScript.
+
+[![CircleCI](https://circleci.com/gh/demouth/mb_strwidth/tree/main.svg?style=svg)](https://circleci.com/gh/demouth/mb_strwidth/tree/main)
+
+## Installation
+
+```sh
+npm install @demouth/mb_strwidth
+```
+
+## Examples
+
+This package has the same result as `mb_strwidth()` in PHP.
+
+```js
+console.log(mb_strwidth('𩸽定食食べたい😭')); // 15
+```
+
+```php
+// PHP 7.3.28
+var_dump(mb_strwidth('𩸽定食食べたい😭')); // int(15)
+```
+
+https://www.php.net/manual/en/function.mb-strwidth.php