## MergerJS JavaScript Style Guide

 

## Files

All files **must** start with the **MergerJS** copyright information as a comment,
with the exception of the ***merger.js*** file which must start with the shebang `#!/usr/bin/env node` before the copyright information.\
The license headers **must** be followed by `'use strict'`;

### Naming

Filenames must be [`camelCase`](https://en.wikipedia.org/wiki/Camel_case).

### Encoding

[UTF-8](https://en.wikipedia.org/wiki/UTF-8)

### Whitespace

- Use **spaces**, not tabs.
- Lines ([line breaks](https://en.wikipedia.org/wiki/Newline)) should end in `LF` characters (UNIX)
  and not `CRLF` (Windows).

 

## Code Formating

## Identation

Use two (2) spaces.

## Semicollons

All expresions **must** end with a semicollon.

Example:

`
doThis();
`

`
const PI = 3.14;
`

### Variables and Constants

- `const`\
Static constant values **must** have the `PASCAL_ALL_CAPS` style.\
In case they are constant value variables from function calls, they **must** have the `camelCase` style.\
If you don't expect the value to change, always opt to use `const`.

- `let`\
Variables **must** have the `camelCase` style.

- `var`\
**Never** use `var`.

Variables and constants **should** have JSDoc type definitions
  ([Official specification](https://jsdoc.app/index.html),
  [Wikipedia](https://en.wikipedia.org/wiki/JSDoc)) documentation when suited,
  or if you think it will improve the readability or development of the code.

### String

You **must** use single quotes ` const MESSAGE = 'Hello World!'; `.

### Spacing

You **must** insert a space after opening and before closing non-empty parenthesis.

Example:

`
doThis( 'with this string' );
`

### Braces

Braces **must** be used in all control structures (i.e. if, else, for, do, while, as well as any others),
even if the body contains only a single statement.

Example:

```js
if ( something ) {
  doThis( 'now' );
}
```

### Conditionals

The `else` statement **must** be separated by an extra line break.

Example:

```js
if ( isNight ) {
  console.log( 'Good night!' );

} else {
  console.log( 'Good day!' );
}
```

### Classes

- Classes **must** have `PascalCase` as naming style.
- Methods and properties **must** have `camelCase` naming style.
- Private methods and properties (methods and properties that will be used only by that class),
  **must** start with four (4) undescores characters in their name.
- Always prefer using classes instead of functions.
- Most classes will be static, so those **must** inherit from `models/staticClassBase.js`.
- Methods **must** have JSDoc
  ([Official specification](https://jsdoc.app/index.html), [Wikipedia](https://en.wikipedia.org/wiki/JSDoc)) documentation.

### Functions

- If it's a module, try to create a class instead, but, if it makes sense, do use a function.
- Do **NOT** create constructor functions, use well structured classes instead.
- Functions names **must** have the `camelCase` naming convention.
- Private functions (internal functions in a class or module)
  **must** start with four (4) undescores characters in their name:

  `const ____privateFunction = ...`

- Functions **must** have JSDoc
  ([Official specification](https://jsdoc.app/index.html), [Wikipedia](https://en.wikipedia.org/wiki/JSDoc)) documentation.
- Functions **must** follow the ES arrow function syntax and use the `const` keyword when they are
  a defenition and not part of an object.
- Parameters **must** have parenthesis, even if the function only has one parameter.
- Lambdas **must** have braces, even if there is only only one expression inside the function.

Example:

```js
/**
 * Description of the function and what it returns.
 *
 * @param { string } withThis Description of the parameter.
 *
 * @returns { void }
 */
const doThis = ( withThis ) => {
  console.log( withThis );
};
```

 

## Don't do things like this:

```js
// No:
let var1, var2, var3;

// Yes:
let var1;
let var2;
let var3;
```

```js
// No:
listArray[listSize++] = it;

// Yes:
listArray[listSize + 1] = it;
++listsSize;
```

 

---

 

After following these style conventions, you should also follow the Airbnb style guide:
https://github.com/airbnb/javascript

 

---

***This document may change in the future.***

---

## Disclaimer for other Developers

Before starting to contribute to MergerJS, you must have in mind that this was my first
software project, before any kind of personal or professional experience.\
The first version was made in one weekend and, with time, it was added new features without
really thinking about future maintainability and evolution.\
Therefore, there are a lot of architectural problems and "spaghetti" code.\
With each new release, the codebase gets small architectural refactorings and improvements,
but **a lot** of work still needs to be done.