import/no-unused-modules

An export that nothing imports is dead code that looks alive, so it still gets maintained, tested and refactored. This rule reads the project's files, collects what each one imports, and reports the exports that are left over.

The rule does nothing until you turn on unusedExports or missingExports.

unusedExports only works in a project with an ESLint 8 config. It needs an .eslintrc file, or eslintConfig in package.json, in or above every folder it searches. Without one it reports nothing, so it has no effect in a project that only has a bunfig.toml.

Configure#

Off by default. To turn it on:

bunfig.toml

[lint.rules]
"import/no-unused-modules" = "error" # or "warn"

Examples#

Reported, because nothing imports formatTime:

shop/.eslintrc.json

{
  "root": true,
  "plugins": ["import"],
  "parserOptions": { "ecmaVersion": "latest", "sourceType": "module" },
  "rules": { "import/no-unused-modules": ["error", { "unusedExports": true }] }
}

shop/app.js

import { formatDate } from "./format.js";

console.log(formatDate(new Date()));

shop/format.jswith { "unusedExports": true, "src": ["shop"] }1 problem

export function formatDate(date) {}
export function formatTime(date) {}

Not reported, with the same two other files:

shop/.eslintrc.json

{
  "root": true,
  "plugins": ["import"],
  "parserOptions": { "ecmaVersion": "latest", "sourceType": "module" },
  "rules": { "import/no-unused-modules": ["error", { "unusedExports": true }] }
}

shop/app.js

import { formatDate } from "./format.js";

console.log(formatDate(new Date()));

shop/format.jswith { "unusedExports": true, "src": ["shop"] }No problems

export function formatDate(date) {}
function formatTime(date) {}

Here's what counts as a use:

import * as format from "./format.js" and import("./format.js") use every export in the file.
export * from "./format.js" uses every export except the default.
require("./format.js") uses nothing.

Options#

Option	Default	What it does
`unusedExports`	`false`	Report exports that no other file imports.
`missingExports`	`false`	Report files that export nothing.
`src`	the directory you run `bun lint` in	Files, folders and globs to search for imports. A file outside them isn't checked for unused exports.
`ignoreExports`	`[]`	Files, folders and globs whose exports are never reported, such as entry points and tests.
`ignoreUnusedTypeExports`	`false`	Don't report an unused exported `type`, `interface` or `enum`.

Only .js, .mjs and .cjs files are searched, unless the import/extensions setting lists others.

The files that main, bin and browser in the closest package.json point to are entry points. Their exports aren't reported, unless the package is "private": true.

With missingExports, this file is reported:

example.jswith { "missingExports": true }1 problem

function formatDate(date) {}

When not to use it#

A library's exports are used by other projects, which the rule can't see. List the public files in ignoreExports, or leave the rule off.