rfdc

Really Fast Deep Clone

build status coverage js-standard-style

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

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:

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.

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: 549.618ms
benchLodashCloneDeep*100: 1461.134ms
benchFastCopy*100: 878.146ms
benchRfdc*100: 323.899ms
benchRfdcProto*100: 314.136ms
benchRfdcCircles*100: 384.561ms
benchRfdcCirclesProto*100: 381.775ms

Tests

npm test

169 passing (342.514ms)

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