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 15% performance boost (see benchmarks).

circles option

Keeping track of circular references will slow down performance with an additional 40%-50% 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: 687.014ms
benchLodashCloneDeep*100: 1803.993ms
benchFastCopy*100: 929.259ms
benchRfdc*100: 565.133ms
benchRfdcProto*100: 484.401ms
benchRfdcCircles*100: 846.672ms
benchRfdcCirclesProto*100: 752.908ms

Tests

npm test

148 passing (365.985ms)

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