not-exist

Check whether packages do not exist in an npm-compatible registry.

Install

npm install not-exist

API

import { notExist } from "not-exist";

await notExist("express");   // false
await notExist("not-exist"); // false

By default, notExist queries npm_config_registry when it is set and otherwise uses the public npm registry. You can provide a different registry, request headers, or an abort signal:

await notExist("example", {
  registry: "https://registry.example.com",
  signal: AbortSignal.timeout(5_000),
  headers: { authorization: "Bearer token" }
});

The function returns true only when the registry responds with HTTP 404. It returns false for a successful response and throws for authentication errors, rate limits, server failures, invalid names, and network failures.

CLI

npx not-exist express some-package-name
npx not-exist --json express some-package-name

The CLI exits with status 0 if every package is absent, 1 if any package exists, and 2 if the check fails.

Caveat

A registry 404 means that the package is not currently visible in that registry. It does not guarantee that the name can be published; registry policy and a concurrent publication can still prevent that.

License

MIT