Lodash Internal `baseAssign` Utility

3.2.0 · abandoned · verified Tue Apr 21

This package provides the internal `baseAssign` function from Lodash version 3.2.0, exporting it as a CommonJS module. `baseAssign` is a low-level utility responsible for shallowly assigning enumerable own properties from source objects to a destination object, serving as a building block for higher-level Lodash methods like `_.assign`. Published in 2015, this specific package is tied to an end-of-life major version of Lodash (v3.x, supported until January 2016). While Lodash (currently v4.x) remains actively maintained with a continuous release cadence, this individual internal module is not independently updated. Modern best practices for consuming Lodash functions involve importing directly from the main `lodash` package (e.g., `require('lodash/assign')` or `import assign from 'lodash/assign'`) or utilizing `lodash-es` with tree-shaking bundlers to optimize bundle size. Per-method packages like this one are discouraged and are slated for removal in Lodash v5.

Common errors

```
baseAssign is not a function
```
cause Attempting to use `import { baseAssign } from 'lodash._baseassign'` in an ES module environment, or `require` with a non-existent path. This package only exports `baseAssign` as a default CommonJS export.

fix For CommonJS, use `const baseAssign = require('lodash._baseassign');`. For ESM, you must use a CommonJS interop layer or, better yet, migrate to `import assign from 'lodash/assign'` from the main `lodash` package.
```
TypeError: baseAssign is not a constructor
```
cause Trying to instantiate `baseAssign` with `new`, which is not a constructor function.

fix `baseAssign` is a utility function and should be called directly, e.g., `baseAssign({}, source)`.

Warnings

breaking This package is based on Lodash v3.2.0, an End-of-Life (EOL) version. Many APIs, behaviors, and internal structures changed significantly in Lodash v4.x, which was released in 2016. Code written for v3.x is unlikely to be directly compatible with v4.x equivalents without migration.
Fix: Migrate to Lodash v4.x by installing `lodash` (the main package). Use `require('lodash/assign')` or `import assign from 'lodash/assign'` instead of `lodash._baseassign`. Consult the Lodash v3 to v4 migration guide.
deprecated Using granular internal modules like `lodash._baseassign` is strongly discouraged by the Lodash team. These packages are considered legacy, can increase `node_modules` size, and are planned for removal in Lodash v5.
Fix: Use specific methods directly from the main `lodash` package (e.g., `require('lodash/assign')` for CommonJS or `import assign from 'lodash/assign'` for ESM with `lodash-es`) or use bundler plugins (like `babel-plugin-lodash`) for optimized builds.
gotcha This package is CommonJS-only, meaning it cannot be directly imported using ES module `import` syntax (`import { baseAssign } from 'lodash._baseassign'`). Attempting to do so will result in runtime errors.
Fix: In CommonJS environments, use `const baseAssign = require('lodash._baseassign');`. For ES module environments, you will need to rely on a CommonJS interop layer or, preferably, use `lodash-es` or `lodash/assign` from the main `lodash` package.
breaking As an EOL version (v3.x), `lodash._baseassign` is no longer supported and will not receive security patches for newly discovered vulnerabilities. While the provided advisories mention v4.x vulnerabilities, similar issues could exist in older codebases.
Fix: Upgrade to the latest stable version of the main `lodash` package (currently v4.x) to ensure you receive critical security updates.

Install

npm install lodash._baseassign npm
yarn add lodash._baseassign yarn
pnpm add lodash._baseassign pnpm

Imports

baseAssign
wrong:
```
import { baseAssign } = from 'lodash._baseassign';
```
correct:
```
const baseAssign = require('lodash._baseassign');
```
This package is CommonJS-only and tied to Lodash v3.x. Native ES module imports are not supported. For modern applications, prefer `import assign from 'lodash/assign'` from the main `lodash` package or `lodash-es` for tree-shaking.

Quickstart

This code demonstrates how to `require` and use the `baseAssign` function for shallow property assignment. It also highlights that `baseAssign` is an internal, low-level utility, contrasting its usage with the public `_.assign` method from the main Lodash library.

const baseAssign = require('lodash._baseassign');

const target = { a: 1 };
const source1 = { b: 2 };
const source2 = { c: 3, a: 4 }; // 'a' will be overwritten by source1 if applied first

// baseAssign is internal and typically takes a single source
const result = baseAssign(target, source1);
console.log('Result after baseAssign(target, source1):', result);
// Expected: { a: 1, b: 2 }

const anotherTarget = {};
const sourceObj = { propA: 1, propB: { nested: true } };
const assignedObj = baseAssign(anotherTarget, sourceObj);
console.log('Assigned object:', assignedObj);
console.log('Is it a shallow copy?', assignedObj.propB === sourceObj.propB); // Should be true

// Demonstrate its internal nature: it's not a public _.assign
// For multiple sources or customizers, use _.assign from the main lodash package.
const _ = require('lodash'); // Using the main lodash package for comparison
const finalObject = _.assign({}, {x: 1}, {y: 2}, {x: 3});
console.log('Result using _.assign from main lodash:', finalObject);

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