Features

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

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.

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

Install

$ npm install --save klona

Modes

There are multiple "versions" of klona available, which allows you to bring only the functionality you need!

klona/json

Size (gzip): 240 bytes Availability: CommonJS, ES Module, UMD Ability: JSON data types

import { klona } from 'klona/json';

klona/lite

Size (gzip): 354 bytes Availability: CommonJS, ES Module, UMD Ability: extends klona/json with support for custom class, Date, and RegExp

import { klona } from 'klona/lite';

klona

Size (gzip): 451 bytes Availability: CommonJS, ES Module, UMD Ability: extends klona/lite with support for Map, Set, DataView, ArrayBuffer, TypedArray

import { klona } from 'klona';

klona/full

Size (gzip): 501 bytes Availability: CommonJS, ES Module, UMD Ability: extends klona with support for Symbol properties and and non-enumerable properties

import { klona } from 'klona/full';

Usage

import { klona } from 'klona';

const input = {
  foo: 1,
  bar: {
    baz: 2,
    bat: {
      hello: 'world'
    }
  }
};

const output = klona(input);

// exact copy of original
assert.deepStrictEqual(input, output);

// applying deep updates...
output.bar.bat.hola = 'mundo';
output.bar.baz = 99;

// ...doesn't affect source!
console.log(
  JSON.stringify(input, null, 2)
);
// {
//   "foo": 1,
//   "bar": {
//     "baz": 2,
//     "bat": {
//       "hello": "world"
//     }
//   }
// }

API

klona(input)

Returns: typeof input

Returns a deep copy/clone of the input.

Benchmarks

Running Node v12.18.3

The benchmarks can be found in the /bench directory. They are separated into multiple categories:

• JSON – compares an array of objects comprised of JSON data types (String, Number, null, Array, Object)
• LITE – like JSON, but adds RegExp, Date and undefined values
• DEFAULT – object with RegExp, Date, Array, Map, Set, custom class, Int8Array, DataView, Buffer values
• FULL – like DEFAULT, but adds Symbol and non-enumerable properties

Important: Only candidates that pass validation step(s) are listed. However, lodash and clone are kept to highlight important differences.

Note: The clone/include candidate refers to its includeNonEnumerable option enabled.

Load times:
  lodash/clonedeep   29.257ms
  rfdc                0.511ms
  clone               0.576ms
  clone-deep          2.494ms
  deep-copy           0.451ms
  klona/full          0.408ms
  klona               0.265ms
  klona/lite          0.308ms
  klona/json          0.263ms

Benchmark :: JSON
  JSON.stringify      x   53,899 ops/sec ±0.76% (92 runs sampled)
  lodash              x   46,800 ops/sec ±0.86% (90 runs sampled)
  rfdc                x  221,456 ops/sec ±0.88% (92 runs sampled)
  clone               x   39,537 ops/sec ±0.68% (92 runs sampled)
  clone/include       x   25,488 ops/sec ±1.06% (88 runs sampled)
  clone-deep          x   99,998 ops/sec ±0.91% (93 runs sampled)
  deep-copy           x  141,270 ops/sec ±0.95% (92 runs sampled)
  klona/full          x   55,016 ops/sec ±0.68% (94 runs sampled)
  klona               x  281,215 ops/sec ±0.77% (93 runs sampled)
  klona/lite          x  318,481 ops/sec ±0.72% (91 runs sampled)
  klona/json          x  334,932 ops/sec ±0.66% (93 runs sampled)

Benchmark :: LITE
  lodash              x   36,992 ops/sec ±0.65% (91 runs sampled)
  clone               x   35,974 ops/sec ±1.13% (88 runs sampled)
  clone/include       x   22,609 ops/sec ±1.02% (91 runs sampled)
  clone-deep          x   92,846 ops/sec ±0.66% (93 runs sampled)
  klona/full          x   47,873 ops/sec ±0.83% (88 runs sampled)
  klona               x  226,638 ops/sec ±1.16% (93 runs sampled)
  klona/lite          x  257,900 ops/sec ±0.82% (93 runs sampled)

Benchmark :: DEFAULT
  lodash              x   55,914 ops/sec ±0.75% (93 runs sampled)
    ✘ Buffer
    ✘ Map keys
  clone               x   92,127 ops/sec ±0.83% (94 runs sampled)
    ✘ DataView
  clone/include       x   62,052 ops/sec ±0.88% (93 runs sampled)
    ✘ DataView
  klona/full          x   90,308 ops/sec ±0.68% (89 runs sampled)
  klona               x  230,257 ops/sec ±0.71% (91 runs sampled)

Benchmark :: FULL
  lodash              x   60,361 ops/sec ±0.65% (91 runs sampled)
    ✘ Buffer
    ✘ Map keys
    ✘ Missing non-enumerable Properties
  clone/include       x   47,263 ops/sec ±0.85% (93 runs sampled)
    ✘ DataView
    ✘ Incorrect non-enumerable Properties
  klona/full          x   82,346 ops/sec ±0.62% (93 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 304 to 489 bytes

License

MIT © Luke Edwards