node-clone-object

Clone object with:

• Circular references
• Property descriptors
• Symbol properties
• Non-enumerable properties

Install

npm i clone-obj
// or
yarn add clone-obj

Requires node >= 6

Usage

const clone = require('clone-obj')
const newObj = clone(obj)

undefined or null

clone-obj will throw TypeError: Cannot clone undefined or null when cloning undefined or null.

Primitive values

clone-obj will return primitive values directly.

clone(1) === 1
clone(true) === true
clone('foo') === 'foo'

Objects

Object created by new operator

clone-obj will use obj.constructor to create new object.

const arr = []
clone(arr) !== arr

const foo = new Date()
const bar = clone(date)
bar !== foo
bar.getTime() === foo.getTime()

const foo = new Buffer('foo')
const bar = clone(date)
Buffer.isBuffer(bar)
bar !== foo
bar.toString() === foo.toString()

Plain object

const foo = { a: 1 }
const bar = clone(foo)
bar !== foo
bar.a === foo.a

Circular references

clone-obj will auto link circular references with cloned objects.

const foo = {}
foo.self = foo
const bar = clone(bar)

foo !== bar
foo.self !== bar.self
bar === bar.self
console.log(bar) // { self: [Circular] }

Property descriptors

clone-obj respects property descriptors.

const foo = {
  get baz () { return this._baz * 2 },
  set baz (val) { this._baz = val }
}
const bar = clone(foo)

typeof bar._baz === 'undefined'
isNaN(bar.baz)
bar.baz = 2
bar._baz === 2
bar.baz === 4

Symbols properties

const sym = Symbol('foo')
const foo = { [sym]: 1 }
const bar = clone(bar)
bar.hasOwnProperty(sym)
bar[sym] === foo[sym]

Non-enumerable properties

const foo = {}
Object.defineProperty(foo, 'baz', {
  enumerable: false,
  value: 1
})
const bar = clone(foo)

const descriptor = Object.getOwnPropertyDescriptor(bar. 'baz')
descriptor.enumrable === false
Object.keys(bar).length === 0
foo.baz === bar.baz === descriptor.value

Arrays

const foo = [1, {}]
const bar = clone(foo)
Array.isArray(foo)
foo !== bar
foo.length === bar.length
foo[0] === bar[0]
foo[1] !== bar[1]

const foo = { a: [1] }
const bar = clone(foo)
Array.isArray(bar.a)
foo.a !== bar.a
foo.a.length === bar.a.length