lint gulpfile, add eslint config and ignore file for those that using eslint

.eslintignore

@@ -0,0 +1,2 @@
+js/**/*.js
+node_modules/**/*.js

.eslintrc.js

@@ -0,0 +1,39 @@
+module.exports = {
+  "root": true,
+  "parserOptions": {
+    "parser": "babel-eslint",
+    "ecmaVersion": 2017,
+    "sourceType": "module"
+  },
+  "env": {
+    "browser": true,
+    "node": true,
+    "es6": true
+  },
+  "globals": {
+    "window": true,
+    "location": true
+  },
+  "extends": [
+    "airbnb-base",
+  ],
+  // custom rules here
+  "rules": {
+    // don"t require .vue extension when importing
+    "import/extensions": ["error", "always", {
+      "js": "never",
+      "vue": "js",
+      "mjs": "never"
+    }],
+    "no-param-reassign": ["error", {
+      "props": true,
+      "ignorePropertyModificationsFor": [
+        "event", // for e.returnvalue
+        "response", // for Express responses
+        "item", // for item usually within each loops
+      ]
+    }],
+    // allow debugger during development
+    "no-debugger": process.env.NODE_ENV === "production" ? 2 : 0
+  }
+}

gulpfile.babel.js

@@ -1,4 +1,3 @@
-/* eslint-disable no-console */
 import gulp from 'gulp';
 import clean from 'gulp-clean';
 import sass from 'gulp-sass';
@@ -20,7 +19,7 @@ import notify from 'gulp-notify';
 import runSequence from 'run-sequence';
 import path from 'path';
 
-const log = console.log;
+const { log } = console;
 let production = false;
 let error = false;
 
@@ -28,8 +27,8 @@ let error = false;
  * Config
  */
 const config = {
-    src: './assets',
-    public: './',
+  src: './assets',
+  public: './',
 };
 
 /**
@@ -44,140 +43,140 @@ const tasks = ['styles', 'scripts', 'images'];
  * @param {string} status
  */
 function notification(message = '', status = 'success') {
-    return gulp.src('./node_modules/gulp-notify/test/fixtures/1.txt')
-        .pipe(notify({
-            title: 'Barebones',
-            message,
-            icon: path.join(__dirname, `assets/icons/${status}.png`),
-        }));
+  return gulp.src('./node_modules/gulp-notify/test/fixtures/1.txt')
+    .pipe(notify({
+      title: 'Barebones',
+      message,
+      icon: path.join(__dirname, `assets/icons/${status}.png`),
+    }));
 }
 
 /**
  * Styles
  */
 gulp.task('clean-styles', () => (
-    gulp.src(`${config.public}/css`, {
-        read: false,
-    })
-        .pipe(clean())
+  gulp.src(`${config.public}/css`, {
+    read: false,
+  })
+    .pipe(clean())
 ));
 
 gulp.task('styles', ['clean-styles'], () => (
-    gulp.src([`${config.src}/styles/*.scss`])
-        .pipe(gulpif(!production, sourcemaps.init()))
-        .pipe(sass({
-            outputStyle: production ? 'compressed' : 'nested',
-        }).on('error', (err) => {
-            notification('Failed to compile styles. 😱', 'error');
-            log(err.stack);
-            error = true;
-        }))
-        .pipe(autoprefixer({
-            browsers: ['last 10 versions'],
-        }))
-        .pipe(rename({
-            suffix: '.min',
-        }))
-        .pipe(gulpif(!production, sourcemaps.write('.')))
-        .pipe(gulp.dest(`${config.public}/css`))
+  gulp.src([`${config.src}/styles/*.scss`])
+    .pipe(gulpif(!production, sourcemaps.init()))
+    .pipe(sass({
+      outputStyle: production ? 'compressed' : 'nested',
+    }).on('error', (err) => {
+      notification('Failed to compile styles. 😱', 'error');
+      log(err.stack);
+      error = true;
+    }))
+    .pipe(autoprefixer({
+      browsers: ['last 10 versions'],
+    }))
+    .pipe(rename({
+      suffix: '.min',
+    }))
+    .pipe(gulpif(!production, sourcemaps.write('.')))
+    .pipe(gulp.dest(`${config.public}/css`))
 ));
 
 /**
  * Scripts
  */
 gulp.task('clean-scripts', () => (
-    gulp.src(`${config.public}/js`, {
-        read: false,
-    })
-        .pipe(clean())
+  gulp.src(`${config.public}/js`, {
+    read: false,
+  })
+    .pipe(clean())
 ));
 
 gulp.task('scripts', ['clean-scripts'], () => {
-    let env = 'development';
-    if (production) {
-        env = 'production';
-    }
+  let env = 'development';
+  if (production) {
+    env = 'production';
+  }
 
-    rollup({
-        entry: `${config.src}/scripts/scripts.js`,
-        plugins: [
-            multiEntry(),
-            buble(),
-            nodeResolve({
-                browser: true,
-                main: true,
-                jsnext: true,
-            }),
-            commonjs({
-                include: [
-                    'node_modules/**',
-                    `${config.src}/**`,
-                ],
-            }),
-            json(),
-            replace({
-                'process.env.NODE_ENV': JSON.stringify(env),
-            }),
-            production ? uglify({}, minify) : '',
+  rollup({
+    entry: `${config.src}/scripts/scripts.js`,
+    plugins: [
+      multiEntry(),
+      buble(),
+      nodeResolve({
+        browser: true,
+        main: true,
+        jsnext: true,
+      }),
+      commonjs({
+        include: [
+          'node_modules/**',
+          `${config.src}/**`,
         ],
-    }).then((bundle) => {
-        bundle.write({
-            format: 'iife',
-            moduleName: 'BarebonesBundle',
-            sourceMap: !production,
-            dest: `${config.public}/js/script.min.js`,
-        });
-    }).catch(err => {
-        notification('Failed to compile scripts. 😱', 'error');
-        log(err.stack);
-        error = true;
+      }),
+      json(),
+      replace({
+        'process.env.NODE_ENV': JSON.stringify(env),
+      }),
+      production ? uglify({}, minify) : '',
+    ],
+  }).then((bundle) => {
+    bundle.write({
+      format: 'iife',
+      moduleName: 'BarebonesBundle',
+      sourceMap: !production,
+      dest: `${config.public}/js/script.min.js`,
     });
+  }).catch((err) => {
+    notification('Failed to compile scripts. 😱', 'error');
+    log(err.stack);
+    error = true;
+  });
 });
 
 /**
  * Watch
  */
 gulp.task('watch-files', tasks, () => {
-    gulp.watch(`${config.src}/styles/**/*.scss`, ['styles']);
-    gulp.watch(`${config.src}/scripts/**/*.js`, ['scripts']);
-    gulp.watch(`${config.src}/images/**/*.*`, ['images']);
+  gulp.watch(`${config.src}/styles/**/*.scss`, ['styles']);
+  gulp.watch(`${config.src}/scripts/**/*.js`, ['scripts']);
+  gulp.watch(`${config.src}/images/**/*.*`, ['images']);
 });
 
 /**
  * Images
  */
 gulp.task('images', () => {
-    // hadle all images that are not svg
-    gulp.src(`${config.src}/images/**/*.*`)
-        .pipe(imagemin({
-            progressive: true,
-            svgoPlugins: [{
-                removeViewBox: false,
-            }],
-        }))
-        .pipe(gulp.dest(`${config.public}/img`));
+  // hadle all images that are not svg
+  gulp.src(`${config.src}/images/**/*.*`)
+    .pipe(imagemin({
+      progressive: true,
+      svgoPlugins: [{
+        removeViewBox: false,
+      }],
+    }))
+    .pipe(gulp.dest(`${config.public}/img`));
 });
 
 /**
  * Main Tasks
  */
 gulp.task('watch', () => (
-    runSequence(tasks, 'watch-files', () => {
-        if (!error) {
-            notification('Watching files... 👀');
-        }
-    })
+  runSequence(tasks, 'watch-files', () => {
+    if (!error) {
+      notification('Watching files... 👀');
+    }
+  })
 ));
 
 gulp.task('build', () => {
-    production = true;
-    runSequence(tasks, () => {
-        if(!error) {
-            notification('Build complete! 🍻');
-        }
-    });
+  production = true;
+  runSequence(tasks, () => {
+    if (!error) {
+      notification('Build complete! 🍻');
+    }
+  });
 });
 
 gulp.task('default', () => (
-    runSequence(tasks)
+  runSequence(tasks)
 ));