App Linter

Having a code linter in place is highly recommended and ensures your code looks legible. It also helps you capture some errors before even running the code.

When you create a Quasar project folder with Quasar CLI it will ask you if you want a linter and which setup you want for ESLint:

Two dot files will be created:

  • .eslintrc.js – ESLint configuration, including rules
  • .eslintignore – what ESLint should ignore when linting

Further extension of one of the Eslint setups above can be made. Your project will by default use eslint-plugin-vue to handle your Vue files. Take a quick look at .eslintrc.js and notice it:

extends: [
  // https://github.com/vuejs/eslint-plugin-vue#priority-a-essential-error-prevention
  // consider switching to `plugin:vue/strongly-recommended` or `plugin:vue/recommended` for stricter rules.
  'plugin:vue/strongly-recommended'
]

If you chose ESLint when creating your project folder, you’ll also notice that /quasar.conf.js adds the eslint-loader to Webpack configuration for you:

build: {
  extendWebpack (cfg) {
    cfg.module.rules.push({
      enforce: 'pre',
      test: /\.(js|vue)$/,
      loader: 'eslint-loader',
      exclude: /[\\/]node_modules[\\/]/
    })
  }
}

Lint Rules

The linting rules can be removed, changed, or added. Notice some things:

  • Some rules are for the Standard, Airbnb or Prettier standards (whichever you chose when project was created). Example: ‘brace-style’.
  • Some rules are for eslint-plugin-vue. Example: ‘vue/max-attributes-per-line’.

You can add/remove/change rules by first visiting https://eslint.org/docs/rules/ or https://github.com/vuejs/eslint-plugin-vue.

Example of ESLint rules below:

// .eslintrc.js

'rules': {
  'brace-style': [2, 'stroustrup', { 'allowSingleLine': true }],

  'vue/max-attributes-per-line': 0,
  'vue/valid-v-for': 0,

  // allow async-await
  'generator-star-spacing': 'off',

  // allow paren-less arrow functions
  'arrow-parens': 0,
  'one-var': 0,

  'import/first': 0,
  'import/named': 2,
  'import/namespace': 2,
  'import/default': 2,
  'import/export': 2,
  'import/extensions': 0,
  'import/no-unresolved': 0,
  'import/no-extraneous-dependencies': 0,

  // allow debugger during development
  'no-debugger': process.env.NODE_ENV === 'production' ? 2 : 0
}

Disabling Linter

In order for you to disable ESLint later, all you need to do is comment out (or remove) the following code from /quasar.conf.js:

build: {
  extendWebpack (cfg) {
    /*
     * we comment out this block
     *
    cfg.module.rules.push({
      enforce: 'pre',
      test: /\.(js|vue)$/,
      loader: 'eslint-loader',
      exclude: /[\\/]node_modules[\\/]/
    })
    */
  }
}