eslint-plugin-asijs — ESLint Rules for AsiJS

Lint AsiJS applications for route hygiene: missing handlers, duplicate registrations, and validation schemas — in your existing ESLint setup (flat config or legacy).

• Package: eslint-plugin-asijs
• Requires: eslint ^8 or ^9 (peer dependency)

Installation

bun add -d eslint eslint-plugin-asijs

Usage — flat config (ESLint 9)

// eslint.config.js
import asijs from "eslint-plugin-asijs";

export default [
  {
    plugins: { asijs },
    rules: {
      "asijs/no-missing-handler": "error",
      "asijs/no-duplicate-route": "warn",
      "asijs/validate-schema": "warn",
    },
  },
];

Or use the built-in preset:

import asijs from "eslint-plugin-asijs";

export default [
  asijs.configs.recommended,
];

Usage — legacy config (ESLint 8)

// .eslintrc.json
{
  "plugins": ["asijs"],
  "extends": ["plugin:asijs/recommended"]
}

Rules

Rule	recommended	Description
asijs/no-missing-handler	error	Routes registered without a handler function
asijs/no-duplicate-route	warn	Duplicate app.get/post/put/... registrations on the same path
asijs/validate-schema	warn	Routes with :param / * segments missing a validation schema
asijs/no-unused-route	off	Excessive route registrations (heuristic — enable via all)

Examples

// Bad — duplicate route + missing handler + no schema on a param route
app.get("/users", () => []);
app.get("/users", () => []);          // no-duplicate-route
app.post("/users/:id");               // no-missing-handler
app.get("/users/:id", () => user);    // validate-schema — no schema for :id

// Good
app.get("/users", () => users);
app.get("/users/:id",
  { schema: { params: { id: { type: "string" } } } },  // any schema object counts
  (ctx) => users.find((u) => u.id === ctx.params.id),
);

Configs

Config	Contents
asijs.configs.recommended	no-missing-handler (error), no-duplicate-route (warn), validate-schema (warn)
asijs.configs.all	every rule, including no-unused-route (warn)

Rule details

no-missing-handler

Flags route registrations with no callback:

app.get("/users");         // ✗ error
app.get("/users", () => []);  // ✓ ok

no-duplicate-route

Detects the same method + path registered twice within the same file:

app.get("/users", a);      // ✓
app.get("/users", b);      // ✗ warn — second registration shadows the first

Note: works per-file; cross-file duplicates (e.g. file-based routing) are intentionally not flagged.

validate-schema

Routes with :param or * (wildcard) segments should carry a validation schema argument. The rule checks that a schema argument exists — it does not introspect the schema's shape:

app.get("/users/:id", () => user);                     // ✗ warn — no schema
app.get("/users/:id", { schema: {} }, () => user);     // ✓ any schema object counts

no-unused-route

Heuristic: flags routes that look dead (registered but never referenced elsewhere). High false-positive risk — opt-in only via asijs.configs.all.

TypeScript & performance

• The rules parse source with ESLint's default parser (ESTree) — no TypeScript parser required for basic checks.
• For monorepos, run ESLint per package or configure --no-warn-ignored to skip workspaces without AsiJS code.