{"id":15462,"library":"lodash.constant","title":"Lodash Constant Function Module","description":"lodash.constant is a standalone npm package providing the `_.constant` utility function, designed for the Lodash v3 ecosystem. It delivers a function that, when called, consistently returns the same, unchanging value that was initially passed to it. This module, currently at version 3.0.0, was last published in January 2015, effectively freezing its functionality to align with the Lodash 3.x release series. While stable for older CommonJS environments, it is not actively maintained and does not receive updates or security patches from the ongoing development of the main Lodash library (which is currently at v4.x and has a healthy, active release cadence). For modern applications targeting Lodash v4+, direct imports like `import constant from 'lodash/constant';` or using `lodash-es` for ES module compatibility and tree-shaking are the recommended approaches, making this standalone module largely a legacy solution.","status":"maintenance","version":"3.0.0","language":"javascript","source_language":"en","source_url":"https://github.com/lodash/lodash","tags":["javascript","lodash","lodash-modularized","stdlib","util"],"install":[{"cmd":"npm install lodash.constant","lang":"bash","label":"npm"},{"cmd":"yarn add lodash.constant","lang":"bash","label":"yarn"},{"cmd":"pnpm add lodash.constant","lang":"bash","label":"pnpm"}],"dependencies":[],"imports":[{"note":"This package exports a default function. For modern Lodash (v4+), prefer `import constant from 'lodash/constant';` for better tree-shaking.","wrong":"import { constant } from 'lodash.constant';","symbol":"constant","correct":"import constant from 'lodash.constant';"},{"note":"This is the primary way to import this specific v3.0.0 standalone package in CommonJS environments, as it exports a default function.","wrong":"const { constant } = require('lodash.constant');","symbol":"constant","correct":"const constant = require('lodash.constant');"},{"note":"This package exports only the `constant` function. For the full Lodash library or other methods, import from `lodash` or `lodash-es` directly.","wrong":"import _ from 'lodash.constant'; // This package only exports constant","symbol":"_","correct":"import constant from 'lodash/constant';"}],"quickstart":{"code":"import constant from 'lodash.constant';\n\nconst getAnswer = constant(42);\nconst getGreeting = constant('Hello, World!');\nconst getObject = constant({ id: 1, name: 'Test' });\n\nconsole.log('The answer is:', getAnswer()); // Expected: The answer is: 42\nconsole.log('The greeting is:', getGreeting()); // Expected: The greeting is: Hello, World!\nconsole.log('The object is:', getObject()); // Expected: The object is: { id: 1, name: 'Test' }\n\n// Demonstrating immutability for constants, modifying the returned object does not affect future calls\nconst myObject = getObject();\nmyObject.name = 'Modified';\nconsole.log('Original object after modification attempt:', getObject()); // Still { id: 1, name: 'Test' }\nconsole.log('Modified object:', myObject); // Expected: { id: 1, name: 'Modified' }","lang":"javascript","description":"Demonstrates how to import and use the `constant` function, showing its consistent return value and immutability."},"warnings":[{"fix":"For new projects or modernizing existing ones, use `import constant from 'lodash/constant';` or `import { constant } from 'lodash-es';` for ES module environments and improved tree-shaking.","message":"This `lodash.constant` v3.0.0 package is based on Lodash v3.x and does not include the significant breaking changes introduced in Lodash v4.0.0 (released 2015) or later versions of the main `lodash` library. Migrating a project using this standalone module to a modern Lodash setup (v4+) will require updating import paths and potentially adapting to other Lodash v4+ API changes.","severity":"breaking","affected_versions":">=3.0.0 <4.0.0"},{"fix":"Migrate to `lodash` or `lodash-es` and import `constant` directly (e.g., `import constant from 'lodash/constant';`) to ensure you benefit from ongoing maintenance and security updates.","message":"The `lodash.constant` standalone package (v3.0.0) is no longer actively maintained or receiving new features/security patches, unlike the main `lodash` library (v4.18.1 and above). Relying on this package may expose applications to unpatched vulnerabilities discovered in the broader Lodash ecosystem.","severity":"gotcha","affected_versions":"3.0.0"},{"fix":"Switch to `import constant from 'lodash/constant';` (for Node.js/Webpack) or `import { constant } from 'lodash-es';` (for ES Modules and tree-shaking bundlers like Rollup/Webpack) to leverage modern optimization techniques.","message":"Using `lodash.constant` in a modern bundler might not provide optimal bundle size or tree-shaking benefits compared to importing directly from `lodash/constant` or using `lodash-es`. Older standalone modules like this one were designed for CJS environments before advanced tree-shaking was common.","severity":"gotcha","affected_versions":"3.0.0"}],"env_vars":null,"last_verified":"2026-04-21T00:00:00.000Z","next_check":"2026-07-20T00:00:00.000Z","problems":[{"fix":"The `require('lodash.constant')` call returns the `constant` *function*. You must first call this function with your desired value to get a new function that will always return that value. Correct usage: `const constantFn = require('lodash.constant'); const getValue = constantFn(42);`","cause":"Attempting to immediately invoke the result of `require('lodash.constant')` as if it were the constant value itself, rather than the function that creates a constant value.","error":"TypeError: require(...) is not a function"},{"fix":"Ensure your environment is set up to handle CommonJS `require` calls, or use `import constant from 'lodash.constant';` if in an ES module context. For modern Lodash usage, consider `import constant from 'lodash/constant';` from the main `lodash` package.","cause":"Attempting to use `require()` in an ES module environment without proper transpilation, or attempting named imports (`{ constant }`) where a default import is expected for this specific package.","error":"Error: Cannot find module 'lodash.constant' or Module not found: Error: Can't resolve 'lodash.constant'"},{"fix":"To access the full Lodash utility belt, you need to install and import the main `lodash` package (e.g., `const _ = require('lodash');` or `import _ from 'lodash';`). `lodash.constant` is a single-function module.","cause":"This specific `lodash.constant` package only provides the `constant` function, not the full `_` object or any other Lodash utilities.","error":"ReferenceError: _ is not defined"}],"ecosystem":"npm"}