feature: setup linting and files changed by linting

.eslintrc

@@ -0,0 +1,37 @@
+{
+  "parserOptions": {
+    "ecmaVersion": 2020,
+    "sourceType": "module",
+    "requireConfigFile": false
+  },
+  "env": {
+    "browser": true,
+    "es6": true,
+    "node": true,
+    "jest": true
+  },
+  "rules": {
+    "no-var": "error",
+    "prefer-const": "warn",
+    "no-console": "off",
+    "no-debugger": "warn",
+    "no-undef": "error",
+    "no-unused-vars": "warn",
+    "quotes": ["error", "single"],
+    "semi": ["error", "never"],
+    "new-cap": 2,
+    "no-caller": 2,
+    "dot-notation": 0,
+    "no-eq-null": 2,
+    "no-unused-expressions": 0,
+    "curly": 0,
+    "eqeqeq": 2,
+    "wrap-iife": [2, "any"],
+    "no-use-before-define": [
+      2,
+      {
+        "functions": false
+      }
+    ]
+  }
+}

.github/workflows/ci.yml

@@ -1,21 +1,49 @@
 name: CI
 
 on:
-  pull_request:
-    branches:
-      - main
   push:
     branches:
       - main
+  pull_request:  
 
 jobs:
+  lint:
+    runs-on: ubuntu-latest
+    concurrency:
+      group: ${{ github.ref }}
+      cancel-in-progress: true
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup NodeJS
+        uses: actions/setup-node@v3
+        with:
+          node-version: 18
+
+      - name: Install dependencies
+        run: npm install --frozen-lockfile
+
+      - name: EsLint
+        run: npm run lint
+
   unit-test:
     runs-on: ubuntu-latest
+    needs: lint
+    concurrency:
+      group: ${{ github.ref }}
+      cancel-in-progress: true
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup NodeJS
+        uses: actions/setup-node@v4
         with:
           node-version: 18
-      - run: |
-          npm install
-          npm run test:unit
+
+      - name: Install dependencies
+        run: npm install --frozen-lockfile
+
+      - name: Unit test
+        run: npm run test:unit

.prettierrc

@@ -0,0 +1,11 @@
+{
+  "singleQuote": true,
+  "trailingComma": "es5",
+  "printWidth": 120,
+  "tabWidth": 4,
+  "semi": false,
+  "bracketSpacing": true,
+  "proseWrap": "always",
+  "arrowParens": "always",
+  "htmlWhitespaceSensitivity": "css"
+}

babel.config.js

@@ -1,4 +1,4 @@
 module.exports = {
     presets: ['@babel/preset-env'],
-    plugins: ['babel-plugin-transform-import-meta']
+    plugins: ['babel-plugin-transform-import-meta'],
 }

gulpfile.js

@@ -1,5 +1,7 @@
 const gulp = require('gulp')
-const {rollup} = require('rollup')
+const eslint = require('gulp-eslint')
+const prettier = require('gulp-prettier')
+const { rollup } = require('rollup')
 const terser = require('@rollup/plugin-terser')
 const babel = require('@rollup/plugin-babel').default
 const commonjs = require('@rollup/plugin-commonjs')
@@ -12,50 +14,59 @@ const babelConfig = {
     ignore: ['node_modules'],
     compact: false,
     extensions: ['.js', '.html'],
-    plugins: [
-        'transform-html-import-to-string'
+    plugins: ['transform-html-import-to-string'],
+    presets: [
+        [
+            '@babel/preset-env',
+            {
+                corejs: 3,
+                useBuiltIns: 'usage',
+                modules: false,
+            },
+        ],
     ],
-    presets: [[
-        '@babel/preset-env',
-        {
-            corejs: 3,
-            useBuiltIns: 'usage',
-            modules: false
-        }
-    ]],
-    configFile: false
+    configFile: false,
 }
 
+gulp.task('lint:js', () =>
+    gulp.src(['./**/*.js', '!node_modules/**', '!plugin/awesoMD/awesoMD*.js']).pipe(eslint()).pipe(eslint.format())
+)
+
+gulp.task('format', () =>
+    gulp.src(['./**/*.js', '!node_modules/**', '!plugin/awesoMD/awesoMD*.js']).pipe(prettier()).pipe(gulp.dest('.'))
+)
 
 gulp.task('build-plugins', () => {
-    return Promise.all([
-        { name: 'RevealAwesoMD', input: './plugin/awesoMD/plugin.js', output: './plugin/awesoMD/awesoMD' },
-    ].map( plugin => {
-        return rollup({
-                cache: cache[plugin.input],
-                input: plugin.input,
-                plugins: [
-                    resolve(),
-                    commonjs(),
-                    babel({
-                        ...babelConfig,
-                        ignore: ["node_modules"],
-                    }),
-                    terser()
-                ]
-            }).then( bundle => {
-                cache[plugin.input] = bundle.cache;
-                bundle.write({
-                    file: plugin.output + '.esm.js',
-                    name: plugin.name,
-                    format: 'es'
-                })
+    return Promise.all(
+        [{ name: 'RevealAwesoMD', input: './plugin/awesoMD/plugin.js', output: './plugin/awesoMD/awesoMD' }].map(
+            (plugin) => {
+                return rollup({
+                    cache: cache[plugin.input],
+                    input: plugin.input,
+                    plugins: [
+                        resolve(),
+                        commonjs(),
+                        babel({
+                            ...babelConfig,
+                            ignore: ['node_modules'],
+                        }),
+                        terser(),
+                    ],
+                }).then((bundle) => {
+                    cache[plugin.input] = bundle.cache
+                    bundle.write({
+                        file: plugin.output + '.esm.js',
+                        name: plugin.name,
+                        format: 'es',
+                    })
 
-                bundle.write({
-                    file: plugin.output + '.js',
-                    name: plugin.name,
-                    format: 'umd'
+                    bundle.write({
+                        file: plugin.output + '.js',
+                        name: plugin.name,
+                        format: 'umd',
+                    })
                 })
-            });
-    } ));
+            }
+        )
+    )
 })

jest.config.js

@@ -1,10 +1,10 @@
 module.exports = {
-    testEnvironment: "node",
-    testMatch: ["**/__tests__/**/*.js", "**/?(*.)+(spec|test).js"],
-    moduleFileExtensions: ["js", "json", "jsx", "node"],
+    testEnvironment: 'node',
+    testMatch: ['**/__tests__/**/*.js', '**/?(*.)+(spec|test).js'],
+    moduleFileExtensions: ['js', 'json', 'jsx', 'node'],
     collectCoverage: true,
     verbose: true,
     transform: {
-        "\\.[j]sx?$": "babel-jest",
-    }
-};
+        '\\.[j]sx?$': 'babel-jest',
+    },
+}

package.json

@@ -4,7 +4,9 @@
   "description": "Revealjs plugin to support markdown with metadata and templates",
   "scripts": {
     "build": "gulp build-plugins",
-    "test:unit": "jest"
+    "test:unit": "jest",
+    "lint": "gulp lint:js",
+    "lint:fix": "gulp format"
   },
   "repository": {
     "type": "git",
@@ -30,6 +32,8 @@
     "core-js": "^3.36.1",
     "front-matter": "^4.0.2",
     "gulp": "^5.0.0",
+    "gulp-eslint": "^6.0.0",
+    "gulp-prettier": "^5.0.0",
     "jest": "^29.7.0",
     "js-yaml": "^4.1.0",
     "marked": "^4.3.0",