.eslintrc.json

{
  "root": true,
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "allowImportExportEverywhere": false,
    "tsconfigRootDir": ".",
    "project": "./tsconfig.json"
  },
  "plugins": [
    "filenames",
    "meteor",
    "@typescript-eslint",
    "deprecation",
    "jolly-roger"
  ],
  "reportUnusedDisableDirectives": true,
  "extends": [
    "airbnb",
    "plugin:meteor/recommended",
    "plugin:import/errors",
    "plugin:import/warnings",
    "plugin:react-hooks/recommended",
    "plugin:eslint-comments/recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:@typescript-eslint/recommended-requiring-type-checking",
    // Make sure to put this last so it can override any other rules
    "prettier"
  ],
  "settings": {
    "import/resolver": {
      "meteor": {
        "extensions": [".js", ".jsx", ".ts", ".tsx"]
      },
      "typescript": {
        "extensions": [".js", ".jsx", ".ts", ".tsx"]
      }
    }
  },
  "rules": {
    // explicit returns can sometimes be more readable and avoid the issue of "I want to return an
    // object literal but ES6 interprets it as a function body with a void expression"
    "arrow-body-style": "off",

    // Publish functions don't really need to be named.
    "func-names": "off",

    // For Match expressions
    "new-cap": [
      "error",
      {
        "capIsNewExceptions": [
          "Optional",
          "OneOf",
          "Maybe",
          "ObjectIncluding",
          "Router"
        ]
      }
    ],

    // sometimes else after a return reads more clearly
    "no-else-return": "off",
    // same for continue
    "no-continue": "off",

    // We sometimes use these in various forms
    "no-underscore-dangle": [
      "error",
      {
        "allow": [
          "_id",
          "_this",
          "_dropIndex",
          "_redirectUri",
          "_postRequest",
          "_anyMethodsAreOutstanding",
          "_schemaKeys",
          "_schema",
          "_retrieveCredentialSecret",
          "_loginStyle",
          "_stateParam",
          "_name",
          "_allSubscriptionsReady",
          "_onMigrate",
          "_def",
          "_makeNewID"
        ]
      }
    ],
    "camelcase": [
      "error",
      {
        "properties": "never",
        "allow": [
          "__meteor_runtime_config__",
          // attempt to capture versioned Google APIs
          "[a-z]+_v[0-9]+"
        ]
      }
    ],

    "no-constant-condition": ["error", { "checkLoops": false }],

    // We have files with multiple React components.  Maybe we should split them out
    // later, but right now I don't want to deal with this
    "react/no-multi-comp": "off",
    "max-classes-per-file": "off",

    // Absolute imports work with Meteor, but aren't well-understood by IDEs, like VS Code
    "import/no-absolute-path": "error",

    // We don't use imports with extensions
    "import/extensions": ["error", "never"],

    // Allow optional imports
    "import/no-extraneous-dependencies": [
      "error",
      {
        "optionalDependencies": true,
        "devDependencies": ["tests/**"]
      }
    ],

    // Imports should be grouped, and sorted within the group. Meteor imports
    // are their own group, after built-ins and before other external libraries
    "import/order": [
      "error",
      {
        "alphabetize": { "order": "asc" },
        "pathGroups": [
          {
            "pattern": "meteor/**",
            "group": "external",
            "position": "before"
          }
        ],
        "pathGroupsExcludedImportTypes": ["builtin"],
        "newlines-between": "never"
      }
    ],

    // Require type-only imports as appropriate - this reduces the size of our
    // runtime bundle
    "@typescript-eslint/consistent-type-imports": [
      "error",
      {
        "prefer": "type-imports"
      }
    ],

    // Files with default exports should be named to match them
    "filenames/match-exported": "error",

    // This is complaining a lot and I don't really want to write dozens of lines of
    // default prop values of `undefined`
    "react/require-default-props": "off",

    // This seems to interact poorly with HOCs like forwardRef. TypeScript means
    // that we don't really have to worry about missing types on our component
    // props
    "react/prop-types": "off",

    // We use spread props a lot for HOCs or other wrapper-type components
    "react/jsx-props-no-spreading": "off",

    // We have methods on classes that don't use this, but still need to be an
    // instance method instead of a class method (e.g. because they're
    // implementing a subset of some larger interface). There's no way to
    // satisfy this linter without breaking those interfaces.
    "class-methods-use-this": "off",

    // Allow tsx files
    "react/jsx-filename-extension": [1, { "extensions": [".jsx", ".tsx"] }],

    // Detect missing deps for non-standard hooks
    "react-hooks/exhaustive-deps": [
      "warn",
      { "additionalHooks": "useTracker|useFind" }
    ],

    // Allow disabling eslint rules on more than a single line, but only across a whole file
    "eslint-comments/disable-enable-pair": [
      "error",
      { "allowWholeFile": true }
    ],

    // Allow void statements to explicitly tag when we're throwing away a promise
    "no-void": ["error", { "allowAsStatement": true }],

    // Relax typescript checks to accommodate existing code
    "@typescript-eslint/no-non-null-assertion": "off",
    "@typescript-eslint/no-unsafe-argument": "off",
    "@typescript-eslint/no-unsafe-assignment": "off",
    "@typescript-eslint/no-unsafe-call": "off",
    "@typescript-eslint/no-unsafe-member-access": "off",
    "@typescript-eslint/no-unsafe-return": "off",
    "@typescript-eslint/no-explicit-any": "off",
    "@typescript-eslint/restrict-template-expressions": "off",
    "@typescript-eslint/no-unused-vars": [
      "error",
      { "argsIgnorePattern": "^_", "varsIgnorePattern": "^_" }
    ],
    "@typescript-eslint/no-namespace": "off",
    "@typescript-eslint/prefer-namespace-keyword": "off",

    // Enable a subset of strict rules that are useful
    "@typescript-eslint/prefer-includes": "error",
    "@typescript-eslint/prefer-optional-chain": "error",
    "@typescript-eslint/prefer-nullish-coalescing": "error",
    "@typescript-eslint/no-base-to-string": "error",
    "@typescript-eslint/no-non-null-asserted-nullish-coalescing": "error",
    "@typescript-eslint/non-nullable-type-assertion-style": "error",
    "@typescript-eslint/prefer-for-of": "error",
    "@typescript-eslint/prefer-return-this-type": "error",
    "@typescript-eslint/prefer-string-starts-ends-with": "error",

    // Enforce safety around promises
    "no-return-await": "off",
    "@typescript-eslint/return-await": "error",

    // There's some risk that this causes us to write parallelizable code that
    // runs in serial, but so far most of the cases where we hit this, we need
    // to run serially, either so we avoid overwhelming a rate limit or because
    // we're paginating over results
    "no-await-in-loop": "off",

    // Show errors for deprecated code
    "deprecation/deprecation": "error",

    // Override Airbnb's style guide to allow "for-of" iteration, which is
    // already supported by Meteor
    "no-restricted-syntax": [
      "error",
      {
        "selector": "ForInStatement",
        "message": "for..in loops iterate over the entire prototype chain, which is virtually never what you want. Use Object.{keys,values,entries}, and iterate over the resulting array."
      },
      {
        "selector": "LabeledStatement",
        "message": "Labels are a form of GOTO; using them makes code confusing and hard to maintain and understand."
      },
      {
        "selector": "WithStatement",
        "message": "`with` is disallowed in strict mode because it makes code impossible to predict and optimize."
      }
    ],

    // Some external libraries (e.g. Bugsnag) require modifying parameter props
    // as part of their interface
    "no-param-reassign": ["error", { "props": false }],

    "jolly-roger/no-disallowed-sync-methods": ["error"],

    // Match existing style
    "prefer-destructuring": "off",
    "no-plusplus": ["error", { "allowForLoopAfterthoughts": true }],
    "react/function-component-definition": [
      "error",
      {
        "namedComponents": "arrow-function"
      }
    ],
    "jsx-a11y/click-events-have-key-events": "off",
    "jsx-a11y/no-static-element-interactions": "off",
    "jsx-a11y/media-has-caption": "off"
  },
  "overrides": [
    {
      "files": ["*.ts", "*.tsx"],
      "rules": {
        // The Javascript versions of these rules don't handle TypeScript
        // scoping correctly, so use the TypeScript-specific ones instead
        "no-use-before-define": "off",
        "@typescript-eslint/no-use-before-define": "error",

        "no-shadow": "off",
        "@typescript-eslint/no-shadow": "error"
      }
    },
    {
      "files": "**/client/**",
      "env": {
        "browser": true
      },
      "rules": {
        "jolly-roger/no-disallowed-sync-methods": "off"
      }
    },
    {
      "files": "eslint/**",
      "parserOptions": { "project": "eslint/tsconfig.json" }
    },
    {
      "files": "**/server/**",
      "env": {
        "node": true
      }
    },
    {
      "files": "types/**",
      "rules": {
        // type declarations for other libraries don't get to choose their
        // export structure
        "import/prefer-default-export": "off",
        // or their variable names
        "no-underscore-dangle": "off",
        // we often need to declare unused variables when extending generic
        // types
        "@typescript-eslint/no-unused-vars": "off"
      }
    },
    {
      "files": "tests/**",
      "rules": {
        // arrow functions with mocha are discouraged
        "func-names": "off",
        "prefer-arrow-callback": "off",

        // since tests run in both client and server context, sometimes we need
        // conditional imports, which can only be easily done with require
        "global-require": "off",
        "@typescript-eslint/no-var-requires": "off",
        "@typescript-eslint/consistent-type-imports": "off"
      }
    }
  ]
}