Registry / http-networking / deferential

deferential

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library1.0.0jsnpmunverified

deferential is a lightweight JavaScript utility designed to assist in building APIs that support both Node.js-style callbacks and native ES6 Promises. It provides a `Deferred` object, which acts as an intermediate for managing the resolution or rejection of a promise, and a `nodeify` method to conditionally return a promise or invoke a callback. The package is at version 1.0.0, indicating a stable but likely infrequent release cadence given its focused scope and the maturity of native Promise implementations. Its key differentiator lies in offering a minimalistic approach to deferred patterns, avoiding the heavier overhead of full-fledged promise libraries like Q or Bluebird by leveraging native browser/Node.js ES6 Promises. It's particularly useful for adapting existing callback-based code to also expose a promise-based interface without rewriting the core logic.

http-networking
npm install deferential
github ↗package ↗
INSTALL
IMPORT
SIG · DEFERENTIAL
D
deferential
http-networkingjavascriptv1.0.0
Install
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Import
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Disk
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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.

Deferred
✓ const Deferred = require('deferential');
✗ import Deferred from 'deferential';
This package is primarily designed for CommonJS environments. While bundlers might process ESM `import` statements, direct use in Node.js ESM modules will likely fail without `createRequire`.
Deferred()
✓ const d = Deferred();
✗ const d = new Deferred();
The `Deferred` function is invoked directly to create an instance, not with `new`.
d.resolver()
✓ fs.readFile(fileName, 'utf8', d.resolver());
✗ fs.readFile(fileName, 'utf8', d.resolve);
`resolver()` returns a thunk that handles Node.js-style (err, data) callbacks, automatically resolving or rejecting the deferred promise.

This code demonstrates how to create a function (`getFile`) that can be consumed with both Node.js-style callbacks and native ES6 Promises using `deferential`.

const Promise = require('native-promise-only'); // Polyfill for older environments const fs = require('fs'); const Deferred = require('deferential'); function getFile(fileName, cb) { const d = Deferred(); fs.readFile(fileName, 'utf8', d.resolver()); return d.nodeify(cb); } // Example usage with callback getFile('myfile.text', function (err, data) { if (err) return console.error('Callback error:', err.message); console.log('Callback data:', data.substring(0, 50) + '...'); }); // Example usage with Promise getFile('myfile.txt') .then(function (data) { console.log('Promise data:', data.substring(0, 50) + '...'); }) .catch(function (err) { console.error('Promise error:', err.message); }); // To make the example runnable, create a dummy file fs.writeFileSync('myfile.text', 'This is some dummy content for the deferential example file. It demonstrates how the package can handle both callback-based and promise-based APIs simultaneously. This makes it easier to migrate or support legacy code while offering modern promise interfaces.'); fs.writeFileSync('myfile.txt', 'This is some dummy content for the deferential example file. It demonstrates how the package can handle both callback-based and promise-based APIs simultaneously. This makes it easier to migrate or support legacy code while offering modern promise interfaces.');
Debug
Known issues
gotchaThe 'deferred' pattern, while implemented by `deferential`, is often considered an anti-pattern in modern JavaScript in favor of directly constructing Promises using `new Promise((resolve, reject) => { ... })`.
fix
For new code, consider using the `new Promise` constructor directly. For adapting callback APIs, ensure the `deferential` pattern is understood and aligns with project conventions.
affects: >=1.0.0
gotchaThis package is primarily designed for CommonJS environments. Attempting to use `import Deferred from 'deferential';` in a native ES module context in Node.js will result in errors.
fix
Use `const Deferred = require('deferential');` in CommonJS modules. For ESM, you might need a bundler like Webpack or Rollup, or use Node.js's `createRequire` function if absolutely necessary.
affects: >=1.0.0
gotchaThe package relies on the global availability of an ES6 `Promise` constructor. In very old or non-standard JavaScript environments, a polyfill for `Promise` might be required.
fix
If `Promise` is undefined, include a polyfill like `native-promise-only` (as shown in the `deferential` README) at the start of your application.
affects: >=1.0.0
Errors
Common errors & fixes
ReferenceError: require is not defined in ES module scope
Attempting to use `require('deferential')` in a JavaScript file that Node.js interprets as an ES module (e.g., due to `.mjs` extension or `"type": "module"` in `package.json`).
fix
Ensure your file is treated as a CommonJS module (e.g., `.js` extension without `"type": "module"`) or use Node.js's `import { createRequire } from 'module'; const require = createRequire(import.meta.url); const Deferred = require('deferential');`.
TypeError: Deferred is not a function
This error typically occurs if `deferential` was imported incorrectly (e.g., `import { Deferred } from 'deferential';`) or if the module failed to load.
fix
Verify that you are using `const Deferred = require('deferential');` in a CommonJS context, and that the package is correctly installed.
ReferenceError: Promise is not defined
The JavaScript environment where `deferential` is being executed does not have a native ES6 Promise implementation.
fix
Add a Promise polyfill (e.g., `require('native-promise-only');`) at the entry point of your application before `deferential` is used.
Upgrade
Version history
1.0.0latest on npm
Audit
Dependencies

No dependency data recorded yet.

Agent activity
7 hits · last 30 days
node
6
OpenAI (training)
1
Resources
githubhttps://github.com/eugeneware/deferential ↗
packagehttps://www.npmjs.com/package/deferential ↗
deferential — npm install deferential · libregistry