node-self/README.md

self property in Node.js

# node-self
🤙 self property in Node.js

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## Table of contents

- [Features](#features)
- [Compatibility](#compatibility)
- [How to use?](#how-to-use)
- [How it works?](#how-it-works)
- [License](#license)

## What is this?

You can use `self` property in Node.js via this module.

```javascript
// In Browser (Window context)
console.log(self); // Window { ... }

// In Browser (Dedicate worker context)
console.log(self); // DedicatedWorkerGlobalScope { ... }

// But, in Node.js
console.log(self); // ReferenceError: self is not defined
```

> Why?: `self` property is not implemented in Node.js.

## Features

You can use `self` property in Node.js.

- Super lightweight
- Pure Javascript
- Zero dependencies

### Compatibility

Both Browser and Node.js.

## How to use?

Just use `self`. It's returns appropriate `Global Object` (Context Dependent)

Import [index.js](./index.js)
```javascript
// CommonJS
require('node-self');

// ES6+
import 'node-self';
```

or paste this code on the top
```javascript
void !function () {
  typeof self == 'undefined'
    && typeof global == 'object'
    && (global.self = global);
}();
```

There are can be `self` (Global Object)

- Browser
  - Window
  - WorkerGlobalScope
    - DedicatedWorkerGlobalScope
    - SharedWorkerGlobalScope
    - ServiceWorkerGlobalScope
- Node.js
  - global

```javascript
self;

// Browser
self === window; // true

// Node.js
self === global; // true
```

## How it works?

This project using `typeof` operator trickly.

`typeof` operator always return a string.
Even with undeclared identifiers, it will return `'undefined'` instead of throwing an error.

```js
undeclared; // ReferenceError: undeclared is not defined

typeof undeclared; // 'undefined'
```

- [MDN Docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof#interaction_with_undeclared_and_uninitialized_variables)
- [ECMA-262 Spec](https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-typeof-operator)

---

- `typeof self == 'undefined'`: Check existing `self` identifier (should be undefined)
- `typeof global == 'object'`: Check current context is Node.js
- `global.self = global`: Define `self` and assign reference of global object

## License

[MIT](./LICENSE)