Javascript: comma-dangle issue

[ccmiller2018]

The issue: creating a 'comma-dangle' error in function. if using --fix, it adds a comma which causes the application to not compile but fixes the error. if i don't add comma, it causes the error in eslint

the specific line causing the issue

{ expiresIn: 28 * 24 * 60 * 60 },

Package.json

```{
"name": "workspace",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "jest",
"start-dev": "nodemon ./bin/www",
"start": "node ./bin/www"
},
"author": "",
"license": "ISC",
"dependencies": {
"bcrypt": "^1.0.3",
"body-parser": "~1.18.2",
"cookie-parser": "~1.4.3",
"debug": "~2.6.9",
"dotenv": "^4.0.0",
"express": "~4.15.5",
"jsonwebtoken": "^8.1.0",
"mongoose": "^4.13.4",
"morgan": "~1.9.0",
"socket.io": "^2.0.4",
"underscore": "^1.8.3",
"uuid": "^3.1.0",
"winston": "^2.4.0",
"winston-daily-rotate-file": "^1.7.2"
},
"devDependencies": {
"eslint": "^4.11.0",
"eslint-config-airbnb": "^16.1.0",
"eslint-config-airbnb-base": "^12.1.0",
"eslint-plugin-import": "^2.8.0",
"eslint-plugin-jsx-a11y": "^6.0.2",
"eslint-plugin-react": "^7.5.1",
"jest": "^21.2.1"
}
}

function creating issue

```router.post('/', (req, res) => {
  User.findOne({ email: req.body.email })
    .then((user) => {
      if (!user) {
        User.create({
          username: req.body.username,
          password: req.body.password,
          email: req.body.email,
          firstname: req.body.firstname,
          surname: req.body.surname,
          id: v4(),
        })
          .then((createduser) => {
            const myToken = jwt.sign(
              { user: user.id },
              'secret',
              { expiresIn: 28 * 24 * 60 * 60 },
            );
            res.json({
              type: 'success',
              payload: {
                token: myToken,
                userId: createduser.id,
                username: createduser.username,
              },
            });
          });
      } else {
        res.json({ type: 'error', payload: 'user already exists' });
      }
    })
    .catch((err) => {
      res.json({ type: 'error', payload: err });
    });
});

[ljharb]

This guide requires you be using https://npmjs.com/babel-preset-airbnb or the equivalent. What's your .eslintrc and .babelrc look like?

(also, you don't need eslint-config-airbnb-base as a top-level dep, if you already have eslint-config-airbnb)

[ccmiller2018]

.eslintrc just extends airbnb. babel isnt being used. would that fix it?

[ljharb]

Absolutely. Our guide and linter config require usage of babel.

[ccmiller2018]

thanks for that. Set up babel, got it running perfectly. thanks for your help :)