convert-cases/README.md

A minimal utility function library that converts camelCase to snake_case and snake_case to camelCase.

# convert-cases

Utilities to convert camelCase to sanke_case and snake_case to camelCase.  
Nested object keys can also be converted together.

## Get started

```
// use npm
$ npm i convert-cases -S

// use Yarn
$ yarn add convert-cases
```

## Usage

4 functions are provided.

- `deeplyCamelize` : Convert all nested object keys to camelCase.
- `deeplySnakize` : Convert all nested object keys to snake_case.
- `snakeToCamel` : Converts single string to camelCase.
- `camelToSnake` : Converts single string to snake_case.

### How to camelCase the keys of nested objects together

```js
import { deeplyCamelize } from 'convert-cases'

const obj = {
  test_case: '1',
  array: [
    { array_case: 1 },
    { array_case: 2 },
  ],
}

deeplyCamelize(obj) // { testCase: '1', array: [ { arrayCase: 1 }, { arrayCase: 2 } ] }
```

#### In the case of TypeScript

You can specify the input and output types using generics:

```ts
deeplyCamelize<BeforeObjType, AfterObjType>(obj)
```

However, both type parameters are optional.
If omitted, the input type will be inferred from the argument, and the output will be inferred as the camelCase equivalent of the input type:

```ts
const result = deeplyCamelize({
  test_case: '1',
  array: [
    { array_case: 1 },
    { array_case: 2 },
  ],
})

// inferred:
// {
//   testCase: '1',
//   array: [
//     { arrayCase: 1 },
//     { arrayCase: 2 },
//   ],
// }
```

The type transformation is recursive and accurately reflects the actual runtime output.

### How to snake_case the keys of nested objects together

```js
import { deeplySnakize } from 'convert-cases'

const obj = {
  testCase: '1',
  array: [
    { arrayCase: 1 },
    { arrayCase: 2 },
  ],
}

deeplySnakize(obj) // { test_case: '1', array: [ { array_case: 1 }, { array_case: 2 } ] }
```

#### In the case of TypeScript

As with `deeplyCamelize`, you can provide both input and output types using generics:

```ts
deeplySnakize<BeforeObjType, AfterObjType>(obj)
```

But both type parameters are optional.
If omitted, the input type is inferred automatically, and the output type will be inferred as the snake_case equivalent:

```ts
const result = deeplySnakize({
  testCase: '1',
  array: [
    { arrayCase: 1 },
    { arrayCase: 2 },
  ],
})

// inferred:
// {
//   test_case: '1',
//   array: [
//     { array_case: 1 },
//     { array_case: 2 },
//   ],
// }
```


#### How to convert a single string to camelCase

```js
import { snakeToCamel } from 'convert-cases'

snakeToCamel('snake_case') // 'snakeCase'
```

#### How to convert a single string to snake_case

```js
import { camelToSnake } from 'convert-cases'

snakeToCamel('camelCase') // 'camel_case'
```