source: trip-planner-front/node_modules/rfdc/readme.md@ b738035

# rfdc

Really Fast Deep Clone


[![build status](https://img.shields.io/travis/davidmarkclements/rfdc.svg)](https://travis-ci.org/davidmarkclements/rfdc)
[![coverage](https://img.shields.io/codecov/c/github/davidmarkclements/rfdc.svg)](https://codecov.io/gh/davidmarkclements/rfdc)
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## Usage

```js
const clone = require('rfdc')()
clone({a: 1, b: {c: 2}}) // => {a: 1, b: {c: 2}}
```

## API

### `require('rfdc')(opts = { proto: false, circles: false }) => clone(obj) => obj2`

#### `proto` option

Copy prototype properties as well as own properties into the new object.

It's marginally faster to allow enumerable properties on the prototype
to be copied into the cloned object (not onto it's prototype, directly onto the object).

To explain by way of code:

```js
require('rfdc')({ proto: false })(Object.create({a: 1})) // => {}
require('rfdc')({ proto: true })(Object.create({a: 1})) // => {a: 1}
```

Setting `proto` to `true` will provide an additional 2% performance boost.

#### `circles` option

Keeping track of circular references will slow down performance with an
additional 25% overhead. Even if an object doesn't have any circular references,
the tracking overhead is the cost. By default if an object with a circular
reference is passed to `rfdc`, it will throw (similar to how `JSON.stringify` \
would throw).

Use the `circles` option to detect and preserve circular references in the
object. If performance is important, try removing the circular reference from
the object (set to `undefined`) and then add it back manually after cloning
instead of using this option.

### `default` import
It is also possible to directly import the clone function with all options set
to their default:

```js
const clone = require("rfdc/default")
clone({a: 1, b: {c: 2}}) // => {a: 1, b: {c: 2}}
```

### Types

`rfdc` clones all JSON types:

* `Object`
* `Array`
* `Number`
* `String`
* `null`

With additional support for:

* `Date` (copied)
* `undefined` (copied)
* `Buffer` (copied)
* `TypedArray` (copied)
* `Map` (copied)
* `Set` (copied)
* `Function` (referenced)
* `AsyncFunction` (referenced)
* `GeneratorFunction` (referenced)
* `arguments` (copied to a normal object)

All other types have output values that match the output
of `JSON.parse(JSON.stringify(o))`.

For instance:

```js
const rfdc = require('rfdc')()
const err = Error()
err.code = 1
JSON.parse(JSON.stringify(e)) // {code: 1}
rfdc(e) // {code: 1}

JSON.parse(JSON.stringify({rx: /foo/})) // {rx: {}}
rfdc({rx: /foo/}) // {rx: {}}
```

## Benchmarks

```sh
npm run bench
```

```
benchDeepCopy*100: 457.568ms
benchLodashCloneDeep*100: 1230.773ms
benchCloneDeep*100: 655.208ms
benchFastCopy*100: 747.017ms
benchRfdc*100: 281.018ms
benchRfdcProto*100: 277.265ms
benchRfdcCircles*100: 328.148ms
benchRfdcCirclesProto*100: 323.004ms
```

## Tests

```sh
npm test
```

```
169 passing (342.514ms)
```

### Coverage

```sh
npm run cov
```

```
----------|----------|----------|----------|----------|-------------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files |      100 |      100 |      100 |      100 |                   |
 index.js |      100 |      100 |      100 |      100 |                   |
----------|----------|----------|----------|----------|-------------------|
```

## License

MIT