What is @google-cloud/promisify?
@google-cloud/promisify is a utility library that helps convert callback-based functions to promise-based functions. This is particularly useful for modern JavaScript development where promises and async/await syntax are preferred over traditional callback patterns.
What are @google-cloud/promisify's main functionalities?
Promisify a single function
This feature allows you to convert a single callback-based function to a promise-based function. The code sample demonstrates how to use the `promisify` function to convert a traditional callback function into one that returns a promise.
const {promisify} = require('@google-cloud/promisify');
function callbackFunction(arg1, arg2, callback) {
// Simulate an asynchronous operation
setTimeout(() => {
callback(null, 'result');
}, 1000);
}
const promiseFunction = promisify(callbackFunction);
promiseFunction('arg1', 'arg2').then(result => {
console.log(result); // 'result'
}).catch(err => {
console.error(err);
});
Promisify all functions in an object
This feature allows you to promisify all functions in an object. The code sample demonstrates how to use the `promisifyAll` function to convert all callback-based functions in an object to promise-based functions, appending 'Async' to the function names.
const {promisifyAll} = require('@google-cloud/promisify');
const obj = {
callbackFunction(arg1, arg2, callback) {
setTimeout(() => {
callback(null, 'result');
}, 1000);
}
};
promisifyAll(obj);
obj.callbackFunctionAsync('arg1', 'arg2').then(result => {
console.log(result); // 'result'
}).catch(err => {
console.error(err);
});
Other packages similar to @google-cloud/promisify
util.promisify
The `util.promisify` function is a built-in Node.js utility that converts callback-based functions to promise-based functions. It is similar to @google-cloud/promisify but is part of the Node.js standard library, making it a more straightforward choice for many developers.
bluebird
Bluebird is a fully-featured promise library that includes a `promisify` function to convert callback-based functions to promise-based ones. It offers more features and better performance compared to @google-cloud/promisify, but it is a larger library and may be overkill for simple use cases.
pify
Pify is a lightweight library that provides a simple way to promisify callback-based functions. It is similar to @google-cloud/promisify but is more minimalistic and has fewer dependencies, making it a good choice for smaller projects.