@endo/eslint-plugin

ESLint rules and shareable configs for Hardened JavaScript and Endo packages.

Installation

npm install --save-dev eslint @endo/eslint-plugin

Usage

ESLint 9+ (Flat Config)

In your eslint.config.js (or .mjs/.cjs):

import endoPlugin from '@endo/eslint-plugin';

export default [
  // Apply the recommended rules for Hardened JS code.
  ...endoPlugin.configs['flat/recommended'],
];

ESLint 8 (Legacy Config)

In your .eslintrc.json (or .eslintrc.js, etc.):

{
  "extends": ["plugin:@endo/recommended"]
}

Shareable Configs

recommended / flat/recommended

Core rules for code written to run under Hardened JavaScript (post-lockdown()).

// flat config
...endoPlugin.configs['flat/recommended']

// legacy
{ "extends": ["plugin:@endo/recommended"] }

Breaking change (v3): This config no longer bundles @jessie.js/eslint-plugin. Consumers who want the Jessie safe-await-separator rule and the use-jessie processor must install @jessie.js/eslint-plugin and configure it directly:

import jessie from '@jessie.js/eslint-plugin';
import endo from '@endo/eslint-plugin';

export default [
  ...endo.configs['flat/recommended'],
  ...jessie.configs['flat/recommended'],
  { processor: jessie.processors['use-jessie'] },
];

recommended-requiring-type-checking / flat/recommended-requiring-type-checking

Extends recommended and adds the restrict-comparison-operands rule, which requires TypeScript type information.

// flat config
...endoPlugin.configs['flat/recommended-requiring-type-checking']

// legacy
{ "extends": ["plugin:@endo/recommended-requiring-type-checking"] }

style / flat/style

Opinionated JS coding-style rules: @stylistic/eslint-plugin, jsdoc, and prettier.

...endoPlugin.configs['flat/style']

imports / flat/imports

Rules about how packages should use imports: require file extensions, disallow extraneous dependencies, prefer named exports.

...endoPlugin.configs['flat/imports']

strict / flat/strict

style + imports + recommended in one config.

...endoPlugin.configs['flat/strict']

internal / flat/internal

The opinionated baseline used by all packages within the Endo monorepo itself. Extends strict and adds TypeScript-ESLint. Not intended for external use.

...endoPlugin.configs['flat/internal']

ses / flat/ses

Extends internal with strict global-variable restrictions for SES bootstrap code that runs before lockdown().

...endoPlugin.configs['flat/ses']

daemon / flat/daemon (deprecated)

Alias for internal/flat/internal.

Rules

| Rule | Description | Fixable | |------|-------------|---------| | @endo/assert-fail-as-throw | Make assert.fail() count as a throw in ESLint's control-flow analysis | — | | @endo/harden-exports | Ensure each named export is immediately followed by harden() | 🔧 | | @endo/no-assign-to-exported-let-var-or-function | Disallow reassignment of exported let/var/function bindings | — | | @endo/no-harden-pattern-maker | Warn when hardening pattern-maker return values (they are already hardened) | — | | @endo/no-multi-name-local-export | Disallow exporting the same local binding under multiple names | — | | @endo/no-polymorphic-call | Disallow method calls on non-local receiver objects | — | | @endo/restrict-comparison-operands | Restrict </>/<=/>= to operands of compatible types | — |

Configuring Individual Rules

// flat config
export default [
  {
    plugins: { '@endo': endoPlugin },
    rules: {
      '@endo/harden-exports': 'error',
      '@endo/no-polymorphic-call': 'warn',
    },
  },
];

// legacy (.eslintrc.json)
{
  "plugins": ["@endo"],
  "rules": {
    "@endo/harden-exports": "error",
    "@endo/no-polymorphic-call": "warn"
  }
}

Compatibility

| ESLint version | How to use | |----------------|------------| | 9.x | eslint.config.js flat config, use flat/* configs | | 8.x | .eslintrc.* legacy config, use bare config names |

The plugin ships both legacy (recommended, internal, …) and flat (flat/recommended, flat/internal, …) configs so you can use whichever ESLint version your project requires.