klona

library2.0.6jsnpmunverified

klona is a minimalist, high-performance utility for deep cloning JavaScript objects, arrays, dates, regexps, and other complex data types. Currently stable at version 2.0.6, it maintains a regular release cadence with frequent patches and minor improvements, as seen with multiple patch releases since v2.0.0. Its primary differentiator lies in its tiny footprint (ranging from 240B for `klona/json` to 501B for `klona/full` gzipped) and superior speed compared to many alternatives. It offers multiple "modes" (`klona/json`, `klona/lite`, `klona`, `klona/full`), allowing developers to import only the necessary functionality for specific data type support, thereby optimizing bundle size. It supports ESM, CommonJS, and UMD, and ships with TypeScript types.

serialization

npm install klona

github ↗package ↗

INSTALL

IMPORT

SIG · KLONA

klona

serializationjavascriptv2.0.6

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

klona

✓ import { klona } from 'klona';

✗ import klona from 'klona';

Since v2.0.0, `klona` uses named exports for ESM. For CommonJS, use `const { klona } = require('klona');`

klona (JSON mode)

✓ import { klona } from 'klona/json';

✗ import klona from 'klona/json';

The `klona/json` entry point provides a smaller bundle for cloning only JSON-serializable types. Uses named exports since v2.0.0.

klona (Full mode)

✓ import { klona } from 'klona/full';

✗ import klona from 'klona/full';

The `klona/full` entry point provides the most comprehensive cloning, including Symbol and non-enumerable properties. Uses named exports since v2.0.0.

klona (CommonJS)

✓ const { klona } = require('klona');

✗ const klona = require('klona');

Since v2.0.0, `klona` uses named exports for CommonJS.

Demonstrates how to import and use the `klona` function to perform a deep clone of a complex object, including nested objects, dates, regexps, sets, and maps, and verifies that modifications to the clone do not affect the original source object.

import { klona } from 'klona'; const input = { foo: 1, bar: { baz: 2, bat: { hello: 'world' } }, date: new Date(), regex: /test/g, items: new Set([1, 2, 3]), mapData: new Map([['a', 1], ['b', 2]]) }; const output = klona(input); // Verify deep equality (requires an assertion library like Node's assert.deepStrictEqual) // import * as assert from 'assert'; // assert.deepStrictEqual(input, output); // Modifying the clone does not affect the original output.bar.bat.hola = 'mundo'; output.bar.baz = 99; output.items.add(4); output.date.setFullYear(2030); console.log('Original Input:', JSON.stringify(input, null, 2)); console.log('Cloned Output (modified):', JSON.stringify(output, null, 2)); // You would see 'hola' and 'mundo' only in the output, and 'baz' will be 99. // The date and set will also reflect the changes only in the output.

Debug

Known issues

breakingStarting with v2.0.0, `klona` migrated from a default export to a named export. This affects both ESM `import` statements and CommonJS `require` calls.

fix

Update your imports: For ESM, change `import klona from 'klona'` to `import { klona } from 'klona'`. For CommonJS, change `const klona = require('klona')` to `const { klona } = require('klona')`. This applies to all `klona` modes (e.g., `klona/json`, `klona/lite`).

affects: >=2.0.0

gotchaPrior to v2.0.5, `klona` and `klona/lite` had an issue where `Object.assign` within class constructors was not handled correctly during cloning, potentially leading to incorrect copies for custom class instances.

fix

Upgrade to `klona@2.0.5` or newer to ensure correct handling of `Object.assign` in class constructors.

affects: <2.0.5

gotchaIn `klona/full`, prototype methods were not consistently copied prior to v2.0.4, which could lead to incomplete deep clones for objects with prototype chains.

fix

Upgrade to `klona@2.0.4` or newer to ensure that prototype methods are correctly copied when using the `klona/full` module.

affects: <2.0.4

gotchaVersions prior to v1.1.1 had issues correctly handling `Set` and `Map` instances during cloning, and lacked explicit protection against `__proto__` pollution attacks.

fix

Upgrade to `klona@1.1.1` or newer to resolve issues with `Set` and `Map` cloning and benefit from improved prototype pollution protection.

affects: <1.1.1

gotchaTypeScript users leveraging `moduleResolution: 'nodenext'` in their `tsconfig.json` might encounter type resolution issues with `klona` in versions prior to v2.0.6 due to missing 'types' condition in the package's `exports` map.

fix

Upgrade to `klona@2.0.6` or newer to gain proper TypeScript `nodenext` support.

affects: <2.0.6

Errors

Common errors & fixes

TypeError: klona is not a function

Attempting to use `klona` as a default import/require after the v2.0.0 breaking change to named exports.

fix

For ESM, change `import klona from 'klona'` to `import { klona } from 'klona'`. For CommonJS, change `const klona = require('klona')` to `const { klona } = require('klona')`.

Type error: Module ''klona'' has no exported member 'klona'. Did you mean to use 'import klona from 'klona'' instead?

Using an older TypeScript version or configuration with a `klona` version >=2.0.0, where the type definitions might be misinterpreted, or the editor cache is stale.

fix

Ensure your TypeScript version and configuration (`moduleResolution`) are compatible. Clear your editor's TypeScript cache if using VSCode. The correct import for v2+ is `import { klona } from 'klona'`.

Upgrade

Version history

2.0.6latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

14 hits · last 30 days

node

Resources

githubhttps://github.com/lukeed/klona ↗

packagehttps://www.npmjs.com/package/klona ↗