Features

• Super tiny and performant
• Deep clone / recursive copies
• Safely handles complex data types
  Array, Date, Map, Object, RegExp, Set, TypedArray

Unlike a "shallow copy" (eg, Object.assign), a "deep clone" recursively traverses a source input and copies its values — instead of references to its values — into a new instance of that input. The result is a structurally equivalent clone that operates independently of the original source and controls its own values.

Additionally, this module is delivered as:

• ES Module: dist/klona.mjs
• CommonJS: dist/klona.js
• UMD: dist/klona.min.js

Why "klona"? It's "clone" in Swedish.
What's with the sheep? Dolly.

Install

$ npm install --save klona

Usage

1import klona from 'klona';
2
3const input = {
4  foo: 1,
5  bar: {
6    baz: 2,
7    bat: {
8      hello: 'world'
9    }
10  }
11};
12
13const output = klona(input);
14
15// exact copy of original
16assert.deepStrictEqual(input, output);
17
18// applying deep updates...
19output.bar.bat.hola = 'mundo';
20output.bar.baz = 99;
21
22// ...doesn't affect source!
23console.log(
24  JSON.stringify(input, null, 2)
25);
26// {
27//   "foo": 1,
28//   "bar": {
29//     "baz": 2,
30//     "bat": {
31//       "hello": "world"
32//     }
33//   }
34// }

API

klona(input)

Returns: typeof input

Returns a deep copy/clone of the input.

Benchmarks

via Node.js v10.13.0

Validation:
  ✘ JSON.stringify (FAILED @ "initial copy")
  ✘ fast-clone (FAILED @ "initial copy")
  ✔ lodash
  ✔ clone-deep
  ✘ deep-copy (FAILED @ "initial copy")
  ✔ depcopy
  ✔ klona

Benchmark:
  JSON.stringify   x  37,803 ops/sec ±0.68% (89 runs sampled)
  fast-clone       x  24,210 ops/sec ±0.81% (91 runs sampled)
  lodash           x  40,563 ops/sec ±1.10% (94 runs sampled)
  clone-deep       x  85,020 ops/sec ±0.17% (95 runs sampled)
  deep-copy        x 116,139 ops/sec ±0.29% (96 runs sampled)
  depcopy          x  24,392 ops/sec ±0.71% (96 runs sampled)
  klona            x 274,496 ops/sec ±0.15% (99 runs sampled)

Related

• dlv – safely read from deep properties in 120 bytes
• dset – safely write into deep properties in 160 bytes
• dequal – safely check for deep equality in 247 bytes

License

MIT © Luke Edwards