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

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.

default import

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

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

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

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

Benchmarks

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

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