# import/enforce-node-protocol-usage

> Enforce either `node:fs` or `fs` when importing Node.js built-in modules

`"node:fs"` and `"fs"` load the same module. With the prefix, you can see right away that the import is a built-in and not a package from `node_modules`, and no installed package can take its place. Without it, the code also runs on old Node.js versions. This rule keeps a project on one of the two.

It checks `import`, `export { } from`, `import()` and `require()`. There's no default, so your config must say `"always"` or `"never"`.

`--fix` adds or removes the prefix.

{/* Generated by src/codegen/lint-rule-docs.ts. Do not edit this section. */}

## Configure

Off by default. It needs an option:

```toml bunfig.toml
[lint.rules]
# "always" or "never"
"import/enforce-node-protocol-usage" = ["error", "always"]
```

{/* End of the generated section. */}

## Examples

Reported:

{/* bad {"options": ["always"], "count": 4} */}
```js
import fs from "fs";
export { join } from "path";

const os = require("os");
const crypto = await import("crypto");
```

Not reported:

{/* good {"options": ["always"]} */}
```js
import fs from "node:fs";
export { join } from "node:path";

const os = require("node:os");
const crypto = await import("node:crypto");
```

## Options

```toml bunfig.toml
[lint.rules]
"import/enforce-node-protocol-usage" = ["error", "always"]
```

| Option | What it does |
| --- | --- |
| `"always"` | Report a built-in module that's imported without `node:`. |
| `"never"` | Report a built-in module that's imported with `node:`. |

{/* bad {"options": ["never"]} */}
```js
import fs from "node:fs";
```

{/* good {"options": ["never"]} */}
```js
import fs from "fs";
```

Some modules only exist with the prefix, such as `node:test` and `node:sqlite`. `"never"` leaves them alone:

{/* good {"options": ["never"]} */}
```js
import { test } from "node:test";
```