klona

What is klona?

The klona npm package is a JavaScript utility for deep cloning objects. It allows developers to create a deep copy of an object, ensuring that changes to the new object do not affect the original object. This is particularly useful when working with complex data structures or when you need to ensure data immutability.

What are klona's main functionalities?

Deep cloning of objects

This feature allows you to create a deep clone of an object, which means that nested objects are also cloned, and changes to the cloned object do not affect the original object.

{"const klona = require('klona');\nconst original = { a: 1, b: { c: 2 } };\nconst copy = klona(original);\ncopy.b.c = 3;\nconsole.log(original.b.c); // 2\nconsole.log(copy.b.c); // 3"}

Deep cloning of arrays

Similar to object cloning, klona can also deep clone arrays, including nested arrays, ensuring that modifications to the cloned array do not affect the original array.

{"const klona = require('klona');\nconst original = [1, [2, 3], [4, 5]];\nconst copy = klona(original);\ncopy[1][0] = 'changed';\nconsole.log(original[1][0]); // 2\nconsole.log(copy[1][0]); // 'changed'"}

Cloning class instances

klona is capable of cloning instances of classes, allowing you to duplicate an instance and modify the copy without affecting the original instance.

{"const klona = require('klona');\nclass Example {\n  constructor(value) {\n    this.value = value;\n  }\n}\nconst original = new Example(1);\nconst copy = klona(original);\ncopy.value = 2;\nconsole.log(original.value); // 1\nconsole.log(copy.value); // 2"}

Other packages similar to klona

lodash

Lodash is a popular utility library that includes a `cloneDeep` function for deep cloning objects. It is more feature-rich than klona but also larger in size, which might be a consideration for projects where bundle size is a concern.

deep-copy

deep-copy is another npm package that provides deep cloning functionality. It offers similar capabilities to klona but may have different performance characteristics or API nuances.

rfdc

rfdc (Really Fast Deep Clone) is a package that focuses on performance for deep cloning objects and arrays. It claims to be faster than other deep cloning methods, which might make it a preferred choice for performance-critical applications.

README

A tiny (423B) and fast utility to "deep clone" Objects, Arrays, Dates, RegExps, and more!

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/index.mjs
• CommonJS: dist/index.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

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

via Node.js v10.13.0

Load times:
  fast-clone         0.884ms
  lodash/clonedeep  27.716ms
  rfdc               0.782ms
  clone-deep         4.023ms
  deep-copy          0.513ms
  klona              0.333ms

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

Benchmark:
  JSON.stringify   x  36,628 ops/sec ±1.34% (89 runs sampled)
  fast-clone       x  23,518 ops/sec ±1.18% (91 runs sampled)
  lodash           x  33,810 ops/sec ±1.34% (94 runs sampled)
  rfdc             x 181,634 ops/sec ±0.71% (95 runs sampled)
  clone-deep       x  84,558 ops/sec ±0.19% (96 runs sampled)
  deep-copy        x 112,866 ops/sec ±1.26% (94 runs sampled)
  klona            x 220,356 ops/sec ±0.34% (97 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