.eslintrc.json

{
  "parserOptions": {
    // Required for certain syntax usages
    "ecmaVersion": 2018,
    "sourceType": "module"
  },
  "plugins": [
    "promise"
  ],
  "extends": ["airbnb", "plugin:compat/recommended"],
  "env": {
    "browser": true,
    "jquery": true
  },
  "rules": {
    // Removed rule "disallow the use of console" from recommended eslint rules
    "no-console": "off",

    // Make line length longer.
    "max-len": ["error", {
      "code": 120,
      "ignoreTemplateLiterals": true,
      "ignoreUrls": true,
      "ignoreStrings": true,
      "ignoreRegExpLiterals": true
    }],

    // Most of our npm modules are for webpack and thus in devDependencies.
    "import/no-extraneous-dependencies": "off",

    // We use for..of loops and the rest of the airbnb disallowed syntax looks okay?
    "no-restricted-syntax": 0,

    // Client code is clearer with file extension.
    "import/extensions": [2, "always"],

    // Assigning into parameters isn't that hard to read in our code.
    "no-param-reassign": "off",

    // Nothing wrong with plusplus!
    "no-plusplus": "off",

    // Nothing wrong with continue either.
    "no-continue": "off",

    // Disable single-line statements (since we enforce curly braces for all)
    "nonblock-statement-body-position": "off",

    // All blocks require curly braces
    "curly": [2, "all"],

    "comma-dangle": [2, {
      "arrays": "always-multiline",
      "objects": "always-multiline",
      "imports": "never",
      "exports": "never",
      "functions": "never"
    }],

    "object-curly-newline": [2, {
      "ObjectExpression": { "multiline": true, "consistent": true },
      "ObjectPattern": { "multiline": true, "consistent": true },
      "ImportDeclaration": { "multiline": true, "consistent": true },
      "ExportDeclaration": { "multiline": true, "consistent": true }
    }],

    "object-property-newline": 2,

    "function-paren-newline": [2, "multiline-arguments"]
  },
  "settings": {
    "polyfills": [
      "Object.assign",
      "Object.entries"
    ]
  }
}