@prexjs/depd

Deprecate all the things! Mark functions, properties, and messages as deprecated with call-site stack traces.

@prexjs/depd provides API deprecation notifications for libraries and modules. It identifies the exact caller line and file, emits one warning per callsite, and supports the standard process.on('deprecation') event.

Features

• Deprecate functions, methods, and object properties cleanly.
• Automatic call-site discovery so developers know which line in their code invoked the deprecated feature.
• Emits each unique warning only once per callsite to avoid terminal flooding.
• Respects NO_DEPRECATION and TRACE_DEPRECATION environment variables.
• Emits structured deprecation events on process.
• Safe no-op implementation in browser environments.
• Dual ES Module (.mjs) and CommonJS (.cjs) support with TypeScript definitions.

Installation

Install using your preferred package manager:

# npm
npm install @prexjs/depd

# pnpm
pnpm add @prexjs/depd

# Yarn
yarn add @prexjs/depd

# Bun
bun add @prexjs/depd

Quick start

import depd from '@prexjs/depd';

const deprecate = depd('my-package');

// Emit a direct deprecation warning
function oldMethod() {
  deprecate('oldMethod() is deprecated. Use newMethod() instead.');
}

Both default and named exports are supported:

import depd, { type DeprecateFunction } from '@prexjs/depd';

Examples

Deprecating a function wrapper

import depd from '@prexjs/depd';

const deprecate = depd('my-package');

function calculateOld(a: number, b: number) {
  return a + b;
}

// Automatically logs a warning on first call from each location
export const calculate = deprecate.function(
  calculateOld,
  'calculate() is deprecated, use add() instead',
);

Deprecating an object property

import depd from '@prexjs/depd';

const deprecate = depd('my-package');

export const config = {
  active: true,
  legacySetting: 'old-value',
};

deprecate.property(config, 'legacySetting', 'config.legacySetting is deprecated');

Compatibility

@prexjs/depd is designed for Node.js, Deno, Bun, and browser environments. In browsers, deprecation warnings safely no-op to avoid breaking frontend builds.

License

This project is licensed under the MIT License. See LICENSE for the full license text.

Related projects

• prex.js — prex.js monorepo and ecosystem.