feat(basics): eslint, prettier, husky, commitlint, lint-staged, eslin…

…t plugins, etc

.editorconfig

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+root = true
+
+[*]
+indent_style = tab
+indent_size = 2
+end_of_line = lf
+insert_final_newline = true

.eslintrc.json

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+{
+  "extends": [
+    "eslint:recommended",
+    "prettier",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:prettier/recommended"
+  ],
+  "plugins": ["@typescript-eslint"],
+  "parser": "@typescript-eslint/parser",
+  "env": {
+    "node": true
+  },
+  "rules": {
+    "@typescript-eslint/no-explicit-any": "off",
+    "@typescript-eslint/no-non-null-assertion": "off"
+  }
+}

.gitignore

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+# Created by https://www.toptal.com/developers/gitignore/api/macos,node,vercel,yarn,git
+# Edit at https://www.toptal.com/developers/gitignore?templates=macos,node,vercel,yarn,git
+
+### Git ###
+# Created by git for backups. To disable backups in Git:
+# $ git config --global mergetool.keepBackup false
+*.orig
+
+# Created by git when using merge tools for conflicts
+*.BACKUP.*
+*.BASE.*
+*.LOCAL.*
+*.REMOTE.*
+*_BACKUP_*.txt
+*_BASE_*.txt
+*_LOCAL_*.txt
+*_REMOTE_*.txt
+
+### macOS ###
+# General
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+### macOS Patch ###
+# iCloud generated files
+*.icloud
+
+### Node ###
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+.pnpm-debug.log*
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+*.lcov
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Snowpack dependency directory (https://snowpack.dev/)
+web_modules/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional stylelint cache
+.stylelintcache
+
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+.parcel-cache
+
+# Next.js build output
+.next
+out
+
+# Nuxt.js build / generate output
+.nuxt
+dist
+
+# Gatsby files
+.cache/
+# Comment in the public line in if your project uses Gatsby and not Next.js
+# https://nextjs.org/blog/next-9-1#public-directory-support
+# public
+
+# vuepress build output
+.vuepress/dist
+
+# vuepress v2.x temp and cache directory
+.temp
+
+# Docusaurus cache and generated files
+.docusaurus
+
+# Serverless directories
+.serverless/
+
+# FuseBox cache
+.fusebox/
+
+# DynamoDB Local files
+.dynamodb/
+
+# TernJS port file
+.tern-port
+
+# Stores VSCode versions used for testing VSCode extensions
+.vscode-test
+
+# yarn v2
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml
+.yarn/install-state.gz
+.pnp.*
+
+### Node Patch ###
+# Serverless Webpack directories
+.webpack/
+
+# Optional stylelint cache
+
+# SvelteKit build / generate output
+.svelte-kit
+
+### Vercel ###
+.vercel
+
+### yarn ###
+# https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
+
+.yarn/*
+!.yarn/releases
+!.yarn/patches
+!.yarn/plugins
+!.yarn/sdks
+!.yarn/versions
+yarn.lock
+
+# if you are NOT using Zero-installs, then:
+# comment the following lines
+!.yarn/cache
+
+# and uncomment the following lines
+# .pnp.*
+
+# End of https://www.toptal.com/developers/gitignore/api/macos,node,vercel,yarn,git

.husky/commit-msg

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+#!/usr/bin/env sh
+. "$(dirname -- "$0")/_/husky.sh"
+
+npx --no -- commitlint --edit ""

.husky/pre-commit

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+#!/usr/bin/env sh
+. "$(dirname -- "$0")/_/husky.sh"
+
+npx lint-staged

.lintstagedrc.json

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+{
+  "*.{ts,js}": [
+    "yarn lint:fix"
+  ]
+}

README.md

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+# vercel-cors

commitlint.config.js

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+module.exports = {
+	extends: ['@commitlint/config-conventional'],
+}

package.json

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+{
+  "name": "vercel-cors",
+  "version": "1.0.0",
+  "description": "Simple CORS module for vercel serverless functions",
+  "main": "src/main.js",
+  "scripts": {
+    "build": "tsc --build",
+    "lint": "eslint . --cache",
+    "lint:fix": "eslint . --cache --fix",
+    "prepare": "husky install"
+  },
+  "keywords": [
+    "cors",
+    "vercel",
+    "simple",
+    "serverless",
+    "functions"
+  ],
+  "author": "diegoulloao",
+  "license": "MIT",
+  "devDependencies": {
+    "husky": "^8.0.1",
+    "typescript": "^4.8.3",
+    "@commitlint/cli": "^17.1.2",
+    "@commitlint/config-conventional": "^17.1.0",
+    "@typescript-eslint/eslint-plugin": "^5.37.0",
+    "@typescript-eslint/parser": "^5.37.0",
+    "eslint-config-prettier": "^8.5.0",
+    "eslint-plugin-prettier": "^4.2.1",
+    "eslint": "^8.23.1",
+    "lint-staged": "^13.0.3",
+    "prettier": "^2.7.1"
+  },
+  "dependencies": {
+    "@vercel/node": "^2.5.14"
+  }
+}

prettier.config.js

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+module.exports = {
+	singleQuote: true,
+	semi: false,
+	printWidth: 120,
+}

src/main.ts

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+import type { VercelRequest, VercelResponse, VercelApiHandler } from '@vercel/node'
+import type { CorsOptions } from 'types'
+
+export const defaults: CorsOptions = {
+	origin: '*',
+	headers: ['Origin', 'X-Requested-With', 'Content-Type', 'Accept'],
+	methods: ['GET', 'HEAD', 'POST', 'PUT', 'PATCH', 'UPDATE', 'OPTIONS', 'DELETE'],
+	expose: [],
+	maxAge: undefined,
+	credentials: false,
+}
+
+export default (options: Partial<CorsOptions>) => {
+	options = { ...defaults, ...options }
+
+	return (handler: VercelApiHandler): VercelApiHandler => {
+		return function (req: VercelRequest, res: VercelResponse) {
+			if (typeof options.origin === 'boolean' && options.origin === false) {
+				return res.status(403).end('not allowed')
+			}
+
+			if (options.origin !== '*' && req.headers.origin === undefined) {
+				return res.status(403).end('unknown origin')
+			}
+
+			if (typeof options.origin === 'string') {
+				if (options.origin === '*' || options.origin === req.headers.origin) {
+					res.setHeader('Access-Control-Allow-Origin', options.origin)
+				}
+			} else if (options.origin instanceof RegExp) {
+				if (options.origin.test(req.headers.origin as string)) {
+					res.setHeader('Access-Control-Allow-Origin', req.headers.origin as string)
+				}
+			} else {
+				const allowedOrigin: boolean = (options.origin as Array<string | RegExp>).some((h: RegExp | string) =>
+					typeof h === 'string' ? h === req.headers.origin : h.test(req.headers.origin as string)
+				)
+
+				if (allowedOrigin) {
+					res.setHeader('Access-Control-Allow-Origin', req.headers.origin as string)
+				}
+			}
+
+			res.setHeader('Access-Control-Allow-Headers', options.headers!.join(', '))
+			res.setHeader('Access-Control-Allow-Credentials', options.credentials!.toString())
+			res.setHeader('Access-Control-Allow-Methods', options.methods!.join(', '))
+
+			if (options.expose!.length) {
+				res.setHeader('Access-Control-Expose-Methods', options.methods!.join(', '))
+			}
+
+			if (!isNaN(options.maxAge!)) {
+				res.setHeader('Access-Control-Max-Age', options.maxAge!)
+			}
+
+			if (options.origin === '*' || (Array.isArray(options.origin) && options.origin.length > 1)) {
+				res.setHeader('Vary', 'Origin')
+			}
+
+			if (req.method === 'OPTIONS') {
+				return res.status(200).json({ body: 'OK' })
+			}
+
+			return handler.apply(this, [req, res])
+		}
+	}
+}

src/types/index.ts

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+type HttpMethods = 'GET' | 'HEAD' | 'POST' | 'PUT' | 'PATCH' | 'UPDATE' | 'DELETE' | 'OPTIONS'
+
+export interface CorsOptions {
+	origin: string | RegExp | boolean | Array<string | RegExp>
+	headers: string[]
+	methods: HttpMethods[]
+	expose: string[]
+	maxAge: number | undefined
+	credentials: boolean
+}