rfdc

Really Fast Deep Clone

Usage

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

It's 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:

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

If this behavior is acceptable, set proto to true for 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 is the cost). By default if an object with a circular reference is passed in, rfdc 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.

Types

rdfc clones all JSON types:

Object
Array
Number
String
null

With additional support for:

Date (copied)
undefined (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:

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

JSON.parse(JSON.stringify(new Uint8Array([1, 2, 3]))) //  {'0': 1, '1': 2, '2': 3 }
rdfc(new Uint8Array([1, 2, 3])) //  {'0': 1, '1': 2, '2': 3 }

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

Benchmarks

npm run bench

benchDeepCopy*100: 716.764ms
benchLodashCloneDeep*100: 1900.503ms
benchFastCopy*100: 1036.360ms
benchRfdc*100: 408.775ms
benchRfdcProto*100: 411.914ms
benchRfdcCircles*100: 529.198ms
benchRfdcCirclesProto*100: 519.694ms

Tests

npm test

169 passing (625.569ms)

Coverage

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

johnjbarton/rfdc