# node-style-guide

**Repository Path**: mirrors_developit/node-style-guide

## Basic Information

- **Project Name**: node-style-guide
- **Description**: A guide for styling your node.js / JavaScript code. Fork & adjust to your taste.
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-08-08
- **Last Updated**: 2026-08-08

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Node.js Style Guide for 2015

> This is a fork of [felixge/node-style-guide](https://github.com/felixge/node-style-guide)
> that attempts to account for some emergent patterns in my ES6/ES2015 codebases.

This is a guide for writing consistent and aesthetically pleasing node.js code.
It is inspired by what is popular within the community, and flavored with some
personal opinions.

There is a .jshintrc which enforces these rules as closely as possible. You can
either use that and adjust it, or use
[this script](https://gist.github.com/kentcdodds/11293570) to make your own.

This guide was originally created by [Felix Geisendörfer](http://felixge.de/) and is
licensed under the [CC BY-SA 3.0](http://creativecommons.org/licenses/by-sa/3.0/)
license. You are encouraged to fork this repository and make adjustments
according to your preferences.

![Creative Commons License](http://i.creativecommons.org/l/by-sa/3.0/88x31.png)

## Table of contents

* [Tabs for indention](#tabs-for-indention)
* [Newlines](#newlines)
* [No trailing whitespace](#no-trailing-whitespace)
* [Use Semicolons](#use-semicolons)
* [Use single quotes](#use-single-quotes)
* [Opening braces go on the same line](#opening-braces-go-on-the-same-line)
* [Method chaining](#method-chaining)
* [Use let instead of var](#use-let-instead-of-var)
* [Use lowerCamelCase for variables, properties and function names](#use-lowercamelcase-for-variables-properties-and-function-names)
* [Use UpperCamelCase for class names](#use-uppercamelcase-for-class-names)
* [Use UPPERCASE for Constants](#use-uppercase-for-constants)
* [Object / Array creation](#object--array-creation)
* [Use the === operator](#use-the--operator)
* [Use slashes for comments](#use-slashes-for-comments)
* [Object.freeze, Object.preventExtensions, Object.seal, with, eval](#objectfreeze-objectpreventextensions-objectseal-with-eval)
* [Getters and setters](#getters-and-setters)

## Tabs for indention

Use tabs for indentation and set your tab width/stops to 4. This is why `var ` and `let ` are 4-characters.

## Newlines

Use UNIX-style newlines (`\n`), and a newline character as the last character
of a file. Windows-style newlines (`\r\n`) are forbidden inside any repository.

## No trailing whitespace

Just like you brush your teeth after every meal, you clean up any trailing
whitespace in your JS files before committing. Otherwise the rotten smell of
careless neglect will eventually drive away contributors and/or co-workers.

## Use Semicolons

According to [scientific research][hnsemicolons], the usage of semicolons is
a core value of our community. Consider the points of [the opposition][], but
be a traditionalist when it comes to abusing error correction mechanisms for
cheap syntactic pleasures.

[the opposition]: http://blog.izs.me/post/2353458699/an-open-letter-to-javascript-leaders-regarding
[hnsemicolons]: http://news.ycombinator.com/item?id=1547647

## Use single quotes

Use single quotes, unless you are writing JSON.

*Right:*

```js
var foo = 'bar';
```

*Wrong:*

```js
var foo = "bar";
```

## Opening braces go on the same line

Your opening braces go on the same line as the statement.

*Right:*

```js
if (true) {
	console.log('winning');
}
else {
	console.error('losing');
}
```

*Wrong:*

```js
if (true)
{
	console.log('winning');
}
else
{
	console.error('losing');
}
```

*Still Wrong:*

```js
if (true) {
	console.log('winning');
} else {
	console.error('losing');
}
```

Also, notice the use of whitespace before and after the condition statement,
and the newline preceeding `else`.

## Method chaining

One method per line should be used if you want to chain methods.

You should also indent these methods so it's easier to tell they are part of the same chain.

*Right:*

```js
User
	.findOne({ name: 'foo' })
	.populate('bar')
	.exec( (err, user) => {
		return true;
	});
````

*Wrong:*

```js
User
.findOne({ name: 'foo' })
.populate('bar')
.exec((err, user) => {
	return true;
});

User.findOne({ name: 'foo' })
	.populate('bar')
	.exec( (err, user) => {
		return true;
	});

User.findOne({ name: 'foo' }).populate('bar')
.exec( (err, user) => {
	return true;
});

User.findOne({ name: 'foo' }).populate('bar')
	.exec( (err, user) => {
		return true;
	});
````

## Use `let` instead of `var`

Use `let` to declare block-scoped variables. When `let` is not available, use
`var` and collect declarations at the top of the function ([Crockford][crockfordconvention]).

*Right:*

```js
let keys = ['foo', 'bar'];
let values = [23, 42];

let object = {};
while (keys.length) {
	let key = keys.pop();
	object[key] = values.pop();
}
```

*Acceptable:* _(when `let` unavailable)_

```js
var keys = ['foo', 'bar'],
	values = [23, 42],
	object = {},
	key;

while (keys.length) {
	key = keys.pop();
	object[key] = values.pop();
}
```

*Wrong:*

```js
var keys = ['foo', 'bar'];
var values = [23, 42];
var object = {};

while (keys.length) {
	var key = keys.pop();
	object[key] = values.pop();
}
```

[crockfordconvention]: http://javascript.crockford.com/code.html

## Use lowerCamelCase for variables, properties and function names

Variables, properties and function names should use `lowerCamelCase`.	They
should also be descriptive. Single character variables and uncommon
abbreviations should generally be avoided.

*Right:*

```js
var adminUser = db.query('SELECT * FROM users ...');
```

*Wrong:*

```js
var admin_user = db.query('SELECT * FROM users ...');
```

## Use UpperCamelCase for class names

Class names should be capitalized using `UpperCamelCase`.

*Right:*

```js
function BankAccount() {
}
```

*Wrong:*

```js
function bank_Account() {
}
```

## Use UPPERCASE for Constants

Constants declared via ES6 `const` should be uppercase.

*Right:*

```js
// good
const SECOND = 1 * 1000;

function File() {}
// acceptable
File.FULL_PERMISSIONS = 0777;
```

*Wrong:*

```js
// use const when available, or var
let SECOND = 1 * 1000;

function File() {}
// avoid
File.fullPermissions = 0777;
```

## Object / Array creation

Use trailing commas and put *short* declarations on a single line. Only quote
keys when your interpreter complains:

*Right:*

```js
var a = ['hello', 'world'];
var b = {
	good: 'code',
	'is generally': 'pretty',
};
```

*Wrong:*

```js
var a = [
	'hello', 'world'
];
var b = {"good": 'code'
				, is generally: 'pretty'
				};
```

## Use the === operator

Programming is not about remembering [stupid rules][comparisonoperators]. Use
the triple equality operator as it will work just as expected.

*Right:*

```js
var a = 0;
if (a !== '') {
	console.log('winning');
}

```

*Wrong:*

```js
var a = 0;
if (a == '') {
	console.log('losing');
}
```

[comparisonoperators]: https://developer.mozilla.org/en/JavaScript/Reference/Operators/Comparison_Operators

## Do not extend built-in prototypes

Do not extend the prototype of native JavaScript objects. Your future self will
be forever grateful. Polyfills for standard functionality are an exception.

*Right:*

```js
var a = [];
if (!a.length) {
	console.log('winning');
}
```

*Wrong:*

```js
Array.prototype.empty = function() {
	return !this.length;
}

var a = [];
if (a.empty()) {
	console.log('losing');
}
```

## Use descriptive conditions

Any non-trivial conditions should be assigned to a descriptively named variable or function:

*Right:*

```js
var isValidPassword = password.length >= 4 && /^(?=.*\d).{4,}$/.test(password);

if (isValidPassword) {
	console.log('winning');
}
```

*Wrong:*

```js
if (password.length >= 4 && /^(?=.*\d).{4,}$/.test(password)) {
	console.log('losing');
}
```

## Write small functions

Keep your functions short. A good function fits on a slide that the people in
the last row of a big room can comfortably read. So don't count on them having
perfect vision and limit yourself to ~15 lines of code per function.

## Return early from functions

To avoid deep nesting of if-statements, always return a function's value as early
as possible.

*Right:*

```js
function isPercentage(val) {
	if (val < 0) {
		return false;
	}

	if (val > 100) {
		return false;
	}

	return true;
}
```

*Wrong:*

```js
function isPercentage(val) {
	if (val >= 0) {
		if (val < 100) {
			return true;
		} else {
			return false;
		}
	} else {
		return false;
	}
}
```

Or for this particular example it may also be fine to shorten things even
further:

```js
function isPercentage(val) {
	var isInRange = (val >= 0 && val <= 100);
	return isInRange;
}
```

A common case where this is encouraged is for node-style callbacks:

```js
function get(foo, callback) {
	request(foo, (err, res, data) => {
		if (err) return callback(`Error: ${err}`);
		
		// massage data a bit or something
		callback(null, data.thing);
});
```

## Name your closures

Feel free to give *meaningful* closures a name. It shows that you care about them, and
will produce better stack traces, heap and cpu profiles.

Note that babel (incorrectly) does this for you when using object initializer shorthand.

*Right:*

```js
req.on('end', function onEnd() {
	console.log('winning');
});
```

*Wrong:*

```js
req.on('end', function() {
	console.log('losing');
});
```

## No nested closures

Use named functions or arrow functions for callbacks. Do not nest anonymous functions.

*Right:*

```js
setTimeout(function() {
	client.connect(afterConnect);
}, 1000);

function afterConnect() {
	console.log('winning');
}
```

*Right (ES6):*

```js
setTimeout(function() {
	client.connect( () => {
		console.log('winning');
	});
}, 1000);
```

*Wrong:*

```js
setTimeout(function() {
	client.connect(function() {
		console.log('losing');
	});
}, 1000);
```

## Use slashes for comments

Use slashes for both single line and multi line comments. Try to write
comments that explain higher level mechanisms or clarify difficult
segments of your code. Don't use comments to restate trivial things.

*Right:*

```js
// 'ID_SOMETHING=VALUE' -> ['ID_SOMETHING=VALUE', 'SOMETHING', 'VALUE']
var matches = item.match(/ID_([^\n]+)=([^\n]+)/));

// This function has a nasty side effect where a failure to increment a
// redis counter used for statistics will cause an exception. This needs
// to be fixed in a later iteration.
function loadUser(id, cb) {
	// ...
}

var isSessionValid = (session.expires < Date.now());
if (isSessionValid) {
	// ...
}
```

*Wrong:*

```js
// Execute a regex
var matches = item.match(/ID_([^\n]+)=([^\n]+)/);

// Usage: loadUser(5, function() { ... })
function loadUser(id, cb) {
	// ...
}

// Check if the session is valid
var isSessionValid = (session.expires < Date.now());
// If the session is valid
if (isSessionValid) {
	// ...
}
```

## Object.freeze, Object.preventExtensions, Object.seal, with, eval

Crazy shit that you will probably never need. Stay away from it.

## Getters and setters

Do not use setters, they cause more problems for people who try to use your
software than they can solve.

Feel free to use getters that are free from [side effects][sideeffect], like
providing a length property for a collection class.

[sideeffect]: http://en.wikipedia.org/wiki/Side_effect_(computer_science)