thenify
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Package description
The thenify npm package is designed to convert Node.js callback-style functions to functions that return a promise. This is particularly useful when working with older Node.js APIs or third-party libraries that do not natively support promises, allowing developers to write cleaner, more modern asynchronous code using async/await or .then() syntax.
Converting a callback-style function to a promise-returning function
This feature allows you to wrap a traditional Node.js callback-style function, such as `fs.readFile`, in a way that it returns a promise. This enables the use of `.then()` and `.catch()` for cleaner asynchronous control flow.
const thenify = require('thenify');
const fs = require('fs');
const readFile = thenify(fs.readFile);
readFile('example.txt', 'utf8').then(contents => {
console.log(contents);
}).catch(err => {
console.error(err);
});Introduced in Node.js 8, `util.promisify` is a built-in function that converts a callback-based function into a promise-based one. It serves a similar purpose to thenify but is built into the Node.js runtime. Unlike thenify, it does not need to be installed as an external package, offering a more integrated solution for modern Node.js versions.
Bluebird is a comprehensive promise library that offers a wide range of features for working with promises, including but not limited to converting callback-style functions into promises. It provides a method called `.promisify()` which is similar to thenify's functionality. Bluebird promises are known for their performance and additional utility methods not found in native promises, making it a more feature-rich, albeit heavier, alternative.
Pify is another npm package that converts callback-based functions into promises. It offers a simple and lightweight approach similar to thenify but with additional options for customizing the behavior of the promisified function, such as the ability to handle multiple callback arguments or to exclude certain functions from promisification. Pify provides a balance between simplicity and configurability.
Readme
Globally make everything a promise!
Promise.resolve([
Promise.resolve(0),
Promise.resolve(1)
]).then(function (results) {
assert.equal(0, results[0])
assert.equal(1, results[1])
})
DO NOT USE THIS IN LIBRARIES! THIS ADDS METHODS TO THE NATIVE PROTOTYPES AND IS CONSIDERED TERRORISM! ONLY USE THIS IN YOUR APP AND TEST THOROUGHLY!
The current async/await proposal
does not support await [], which is co's
signature to support yielding multiple asynchronous functions in parallel.
There is very little chance of having this overloading being included in the specifications.
However, @domenic had a crazy idea: globally make arrays a promise!. This is what this repository does.
async function () {
var results = await [
true,
Promise.resolve(1)
];
// results[0] === true
// results[1] === 1
}
Just somehow get index.js included in your app.
Node:
require('thenify')
HTML:
<script src="https://cdn.rawgit.com/thenables/thenify/master/index.js"></script>
FAQs
Promisify a callback-based function
The npm package thenify receives a total of 11,868,198 weekly downloads. As such, thenify popularity was classified as popular.
We found that thenify demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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