oxlint-appsync

Oxlint (and ESLint-compatible) plugin that enforces AWS AppSync JavaScript runtime restrictions.

Use it to catch unsupported syntax in AppSync resolver code before deployment.

Install

npm install -D oxlint oxlint-appsync

oxlint-appsync depends on @oxlint/plugins at runtime.

Usage with Oxlint

.oxlintrc.json

Copy oxlintrc.example.json to .oxlintrc.json in your project:

oxlint.config.ts

import { defineConfig } from "oxlint";
import plugin, { portable, recommended } from "oxlint-appsync";

export default defineConfig({
  jsPlugins: [plugin],
  rules: recommended,
  overrides: [
    {
      files: ["src/shared/**/*.js"],
      rules: portable,
    },
  ],
});

Run:

npx oxlint path/to/appsync

Usage with ESLint

The plugin uses Oxlint's createOnce API wrapped with eslintCompatPlugin, so it also works with ESLint:

import appsync from "oxlint-appsync";
import { portable, recommended } from "oxlint-appsync";

export default [
  {
    plugins: { appsync },
    rules: recommended,
  },
  {
    files: ["src/shared/**/*.js"],
    rules: portable,
  },
];

Config presets

| Preset | Use for | | ------------- | ----------------------------------------------------------------------------------------------------------------- | | recommended | AppSync resolver entry points — all syntax rules enabled | | portable | Shared modules that must run in AppSync and other runtimes (e.g. Lambda) — syntax rules plus no-appsync-globals |

Rules

| Rule | Description | | --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | appsync/no-global-constructor | Disallow global constructor calls (String(), Number(), Boolean(), Date(), etc.) | | appsync/no-async-await | Disallow async/await and async functions | | appsync/no-classes | Disallow class declarations and expressions | | appsync/no-context-reassignment | Disallow reassigning context and its base properties | | appsync/no-instanceof | Disallow instanceof | | appsync/no-for-loop | Disallow C-style for loops (for-in / for-of allowed) | | appsync/no-while | Disallow while loops | | appsync/no-do-while | Disallow do-while loops | | appsync/no-disallowed-methods | Disallow unsupported methods (call, apply, bind) | | appsync/no-try | Disallow try/catch/finally | | appsync/no-throw | Disallow throw | | appsync/no-continue | Disallow continue | | appsync/no-labeled-statement | Disallow labeled statements | | appsync/no-new | Disallow the new operator | | appsync/no-regex | Disallow regex literals (/pattern/) | | appsync/no-promise | Disallow Promise usage | | appsync/no-recursion | Disallow recursive function calls | | appsync/no-generators | Disallow generator functions | | appsync/no-this | Disallow this | | appsync/no-update-operators | Disallow ++ and -- | | appsync/no-bitwise-not | Disallow bitwise NOT (~) | | appsync/no-in-operator | Disallow in (use Object.hasOwn) | | appsync/no-function-arguments | Disallow passing functions as call arguments (parity with AWS no-function-passing; inline arrows allowed only on allowlisted Array methods like map, filter) | | appsync/no-function-reassign | Disallow reassigning function variables | | appsync/no-function-return | Disallow returning functions from functions | | appsync/no-appsync-globals | Disallow AppSync-only globals (util, extensions, runtime) — opt-in, included in portable |

Migration

0.3.1 → 0.4.0

Seven new rules are enabled in the recommended and portable presets for parity with @aws-appsync/eslint-plugin:

• appsync/no-regex — regex literals (/pattern/) are not supported; use string patterns for replace, split, etc.
• appsync/no-promise — Promise usage is not supported.
• appsync/no-context-reassignment — reassigning context or its base properties is not supported.
• appsync/no-disallowed-methods — call, apply, and bind are not supported.
• appsync/no-recursion — recursive function calls are not supported.
• appsync/no-function-reassign — reassigning function variables is not supported.
• appsync/no-function-return — returning functions from functions is not supported.

0.3.0 → 0.3.1

appsync/no-function-arguments now matches AWS no-function-passing more closely:

• Inline arrow functions are allowed only on allowlisted Array methods (map, filter, find, some, every, reduce, and similar).
• Array.prototype.sort() with a comparator (inline or by reference) is reported.
• Passing arrow functions to non-allowlisted calls (e.g. run(() => 1)) is reported.

0.1.x → 0.2.0

appsync/no-string-constructor was removed. Use appsync/no-global-constructor instead — it covers String() and other global constructor calls (Boolean(), Number(), Date(), etc.).

Development

Requires Bun.

bun install
bun run build
bun test

References

• Writing Oxlint JS plugins
• AWS AppSync supported runtime features

License

MIT