@putout/plugin-nodejs [![NPM version][NPMIMGURL]][NPMURL]

[NPMIMGURL]: https://img.shields.io/npm/v/@putout/plugin-nodejs.svg?style=flat&longCache=true
[NPMURL]: https://npmjs.org/package/@putout/plugin-nodejs "npm"

> Node.js is an open-source, cross-platform, JavaScript runtime environment.
>
> (c) Nodejs.org

🐊Putout plugin adds ability to transform to new Node.js API and apply best practices.

Install

``
npm i putout @putout/plugin-nodejs -D
`

Rules

- ✅ add-node-prefix;
- ✅ add-missing-strict-mode;
- ✅ convert-buffer-to-buffer-alloc;
- ✅ convert-commonjs-to-esm;
- ✅ convert-dirname-to-url;
- ✅ convert-esm-to-commonjs;
- ✅ convert-exports-to-module-exports;
- ✅ convert-fs-promises;
- ✅ convert-promisify-to-fs-promises;
- ✅ convert-top-level-return;
- ✅ convert-url-to-dirname;
- ✅ declare;
- ✅ declare-after-require;
- ✅ group-require-by-id;
- ✅ remove-process-exit;
- ✅ remove-useless-promisify;
- ✅ remove-top-level-process-exit;
- ✅ remove-useless-strict-mode;
- ✅ remove-illegal-strict-mode;

File rules

- ✅ apply-privately-imported-file;
- ✅ cjs-file;
- ✅ mjs-file;
- ✅ rename-file-cjs-to-js;
- ✅ rename-file-mjs-to-js;

Config

`json
{
"rules": {
"nodejs/add-missing-strict-mode": "on",
"nodejs/add-node-prefix": "on",
"nodejs/convert-commonjs-to-esm": "off",
"nodejs/convert-esm-to-commonjs": "off",
"nodejs/cjs-file": "off",
"nodejs/mjs-file": "off",
"nodejs/rename-file-cjs-to-js": "off",
"nodejs/rename-file-mjs-to-js": "off",
"nodejs/convert-buffer-to-buffer-alloc": "on",
"nodejs/convert-fs-promises": "on",
"nodejs/convert-promisify-to-fs-promises": "on",
"nodejs/convert-dirname-to-url": "on",
"nodejs/convert-exportst-to-module-exports": "on",
"nodejs/convert-url-to-dirname": "on",
"nodejs/convert-top-level-return": "on",
"nodejs/declare": "on",
"nodejs/declare-after-require": "on",
"nodejs/group-require-by-id": "on",
"nodejs/remove-process-exit": "on",
"nodejs/remove-useless-strict-mode": "on",
"nodejs/remove-illegal-strict-mode": "on",
"nodejs/remove-useless-promisify": "on",
"nodejs/remove-top-level-process-exit": "on"
}
}
`

add-node-prefix

> Deno supports using Node.js built-in modules such as fs, path, process, and many more via node: specifiers.
>
> (c) deno.land

Check out in 🐊Putout Editor.

$3

`js
import fs from 'fs';

const path = require('path');
await import('path');
`

$3

`js
import fs from 'node:fs';

const path = require('node:path');
await import('node:path');
`

$3

Linter | Rule | Fix
--------|-------|------------|
🐊 Putout | add-node-prefix | ✅
⏣ ESLint | prefer-node-protocol | ✅

convert-buffer-to-buffer-alloc

> The Buffer() function and new Buffer() constructor are deprecated due to API usability issues that can lead to accidental security issues.
>
> (c) DEP0005

Check out in 🐊Putout Editor.

$3

`js
const n = 100;
const buf = [];

new Buffer(123);
new Buffer(n);
new Buffer('hello');

new Buffer([]);
new Buffer(buf);
`

$3

`js
const n = 100;
const buf = [];

Buffer.alloc(123);
Buffer.alloc(n);
Buffer.from('hello');

Buffer.from([]);
Buffer.from(buf);
`

convert-fs-promises

Convert fs.promises into form that will be simpler to use and convert to and from ESM.

$3

`js
const {readFile} = require('fs').promises;
`

$3

`js
const {readFile} = require('fs/promises');
`

convert-promisify-to-fs-promises

$3

`js
const fs = require('fs');
const readFile = promisify(fs.readFile);
`

$3

`js
const {readFile} = require('fs/promises');
`

convert-dirname-to-url

Only for ESM.

$3

`js
const {join} = require('path');
const path = require('path');

const file1 = join(__dirname, '../../package.json');
const file2 = path.join(__dirname, '../../package.json');
`

$3

`js
const file1 = new URL('../../package.json', import.meta.url);
const file2 = new URL('../../package.json', import.meta.url);
`

convert-url-to-dirname

Only for CommonJS.

$3

`js
const {readFile} = require('fs/promises');
const file = new URL('../../package.json', import.meta.url);
`

$3

`js
const {readFile} = require('fs/promises');
const {join} = require('path');
const file = join(__dirname, '../../package.json');
`

remove-process-exit

In most cases process.exit() is called from bin directory, if not - disable this rule using match.

`diff
-process.exit();
`

remove-top-level-process-exit

Top-level process.exit() has no sense (except debugging).

Checkout in ✅Putout Editor.

`diff
-process.exit();
`

convert-exports-to-module-exports

Since exports = 5 wan't make any export, just change value of variable.
Checkout in 🐊Putout Editor.

$3

`js
exports.x = 5;
`

$3

`js
module.exports.x = 5;
`

convert-top-level-return

$3

`js
return;
`

$3

`js
process.exit();
`

declare

Add declarations to built-in node.js modules:

- buffer;
- child_process;
- events;
- fs;
- path;
- process;
- module;
- stream;
- os;
- url;
- util;
- zlib;
- timers;

Based on @putout/operator-declare.

$3

`js
await readFile('hello.txt', 'utf8');
`

$3

`js
import {readFile} from 'fs/promises';

await readFile('hello.txt', 'utf8');
`

When you want to skip some declaration use dismiss:

`json
{
"rules": {
"nodejs/declare": ["on", {
"dismiss": ["readFile"]
}]
}
}
`

declare-after-require

> Node.js follows the CommonJS module system, and the builtin require function is the easiest way to include modules that exist in separate files. The basic functionality of require is that it reads a JavaScript file, executes the file, and then proceeds to return the exports object.
>
> (c) Nodejs.org

Check out in 🐊Putout Editor.For ESM use esm/declare-imports-first.

$3

`js
const name = 'hello.txt';
const {readFile} = require('fs/promises');
`

$3

`js
const {readFile} = require('fs/promises');
const name = 'hello.txt';
`

convert-commonjs-to-esm/require

Convert CommonJS EcmaScript Modules.

> EcmaScript module syntax is the standard way to import and export values between files in JavaScript. The import statement can be used to reference a value exposed by the export statement in another file.
>
> (c) parceljs

$3

`js
const {join} = require('path');

const args = require('minimist')({
string: ['a', 'b'],
});
`

$3

`js
import {join} from 'path';
import minimist from 'minimist';

const args = minimist({
string: ['a', 'b'],
});
`

convert-commonjs-to-esm/exports

Checkout in 🐊Putout Editor.

$3

`js
module.exports = () => {};
`

$3

`js
export default () => {};
`

convert-commonjs-to-esm/commons

$3

`js
const {readFile} = require('fs/promises');

await readFile(__filename);
`

$3

`js
import {readFile} from 'fs/promises';
import {fileURLToPath} from 'url';

const __filename = fileURLToPath(import.meta.url);
await readFile(__filename);
`

group-require-by-id

Checkout in 🐊Putout Editor. For ESM use esm/group-imports-by-sources.

$3

`js
const ss = require('../../bb/ss');
const d = require('../hello');
const react = require('react');
const {lodash} = require('lodash');
const fs = require('node:fs');
const b = require('./ss');
const m = require(x);
const c = 5;
`

$3

`js
const fs = require('node:fs');
const react = require('react');
const {lodash} = require('lodash');
const ss = require('../../bb/ss');
const d = require('../hello');

const b = require('./ss');
const m = require(x);
const c = 5;
`

convert-esm-to-commonjs

> CommonJS is a module system supported in Node, it provides a require function, which can be used to access the exports object exposed by another file.
>
> (c) parceljs

Convert EcmaScript Modules to CommonJS.

$3

`js
import hello from 'world';
`

$3

`js
const hello = require('world');
`

cjs-file

Run convert-esm-to-commonjs for all *.cjs files with help of redlint.

Check out in 🐊Putout Editor.

mjs-file

Run convert-commonjs-to-esm for all *.cjs files with help of redlint.

Check out in 🐊Putout Editor.

rename-file-cjs-to-js

Rename *.cjs files when type === "commonjs":

`diff
/
|-- package.json
-- lib/
- -- hello.cjs
+ -- hello.js
``

Check out in 🐊Putout Editor.

rename-file-mjs-to-js

Rename *.mjs files when type === "module":

`diff
/
|-- package.json
-- lib/
- -- hello.mjs
+ -- hello.js
``

Check out in 🐊Putout Editor.

add-missing-strict-mode

> Strict mode makes several changes to normal JavaScript semantics:
>
> - Eliminates some JavaScript silent errors by changing them to throw errors.
> - Fixes mistakes that make it difficult for JavaScript engines to perform optimizations: strict mode code can sometimes be made to run faster than identical code that's not strict mode.
> - Prohibits some syntax likely to be defined in future versions of ECMAScript.
>
> (c) MDN

Add strict mode to CommonJS:

$3

`js
const a = require('b');
`

$3

`js
'strict mode';

const a = require('b');
`

$3

remove-useless-strict-mode

Remove 'use strict' from ESM.

$3

`js
'strict mode';

import a from 'b';
`

$3

`js
import a from 'b';
`

remove-illegal-strict-mode

> SyntaxError: "use strict" not allowed in function with non-simple parameters
> The JavaScript exception "use strict" not allowed in function occurs when a use strict directive is used at the top of a function with default parameters, rest parameters, or destructuring parameters.
>
> (c) MDN

Checkout in 🐊Putout Editor.

$3

`ts
function x1(...a) {
'use strict';
}

function x2(a, b = 3) {
'use strict';
}

function x3({a}) {
'use strict';
}

function x4([a]) {
'use strict';
}

function x5(...a) {
'use strict';
}
`

$3

`js
function x1(...a) {}

function x2(a, b = 3) {}

function x3({a}) {}

function x4([a]) {}

function x5(...a) {}
`

remove-useless-promisify

> Takes a function following the common error-first callback style, i.e. taking an (err, value) => ... callback as the last argument, and returns a version that returns promises.
>
> (c) nodejs.org

Remove useless promisify(). Checkout in 🐊Putout Editor.

$3

`js
export const readSize = promisify(async (dir, options, callback) => {});
`

$3

`js
export const readSize = async (dir, options, callback) => {};
`

#### apply-privately-required-to-file

> Entries in the imports field must be strings starting with #.
> Package imports permit mapping to external packages.
> This field defines subpath imports for the current package.
>
> (c) nodejs.org

Let's consider file structure:

`
/
|-- package.json {"imports": {"#is: {"default": "./lib/tokenize/is.js"}}}
|-- lib/
| -- tokenize/
| -- is.js "export const isPrev = () => {}"
| -- expressions/
-- spread-element.js "const {isPrev} = require('../is.js')"
`

In this case spread-element.js can be fixed:

#### ❌ Example of incorrect code

`js
const {isPrev} = require('../is.js');
`

#### ✅ Example of correct code

`js
const {isPrev} = require('#is');
``

License

MIT