shallow-clone-shim

shallow-clone-shim

Shallow clones an object, including non-enumerable properties, while respecting the original data and accessor descriptors of the properties. This means that for instances getters and setters are copied faithfully. Optionally allows for shimming/overwriting properties by redefining or manipulating existing property descriptors.

Installation

npm install shallow-clone-shim --save

Usage

const assert = require('assert')
const clone = require('shallow-clone-shim')

const original = Object.defineProperties({}, {
  foo: { // non-writable
    value: 1
  },
  bar: { // non-configurable
    enumerable: true,
    get: function get () {
      return 2
    }
  }
})

assert.strictEqual(original.foo, 1)
assert.strictEqual(original.bar, 2)

const copy = clone({}, original, {
  bar (descriptor) {
    // descriptor == Object.getOwnPropertyDescriptor(original, 'bar')
    const getter = descriptor.get
    descriptor.get = function get () {
      return getter() + 1
    }
    return descriptor
  }
})

assert.strictEqual(original.foo, 1)
assert.strictEqual(original.bar, 3)

API

object = clone(object, original[, shim])

Shallow copies all own properties of the original into object. Both enumerable and non-enumerable properties are copied.

The object is also returned.

If the optional shim argument is supplied, it's expected to be an object containing functions. The names of the shim object propeties is expected to match the names of properties in the original object. Each shim function is called with the property descriptor for that particular property in original. The function is expected to return a valid property descriptor as expected by Object.defineProperty(). The returned desciptor will replace the original descriptor in the copied object.

License

MIT