@braintree/wrap-promise

What is @braintree/wrap-promise?

@braintree/wrap-promise is a utility library that helps in converting callback-based functions into promise-based ones. This is particularly useful for modernizing codebases and making asynchronous code easier to read and maintain.

What are @braintree/wrap-promise's main functionalities?

Wrap a callback-based function

This feature allows you to wrap a traditional callback-based function and convert it into a promise-based function. This makes it easier to work with asynchronous code using modern JavaScript syntax.

const wrapPromise = require('@braintree/wrap-promise');

function callbackFunction(arg, callback) {
  setTimeout(() => {
    if (arg) {
      callback(null, 'Success');
    } else {
      callback('Error');
    }
  }, 1000);
}

const promiseFunction = wrapPromise(callbackFunction);

promiseFunction(true)
  .then(result => console.log(result))
  .catch(error => console.error(error));

Wrap a function with multiple arguments

This feature demonstrates how to wrap a function that takes multiple arguments before the callback. The wrapped function can then be used as a promise-based function.

const wrapPromise = require('@braintree/wrap-promise');

function multiArgFunction(arg1, arg2, callback) {
  setTimeout(() => {
    if (arg1 && arg2) {
      callback(null, 'Success');
    } else {
      callback('Error');
    }
  }, 1000);
}

const promiseFunction = wrapPromise(multiArgFunction);

promiseFunction('arg1', 'arg2')
  .then(result => console.log(result))
  .catch(error => console.error(error));

Other packages similar to @braintree/wrap-promise

util.promisify

The `util.promisify` function in Node.js standard library serves a similar purpose by converting callback-based functions to promise-based ones. It is a built-in utility and does not require an additional package, making it a convenient option for Node.js developers.

bluebird

Bluebird is a fully-featured promise library that includes a `promisify` method to convert callback-based functions to promises. It offers more advanced features and better performance compared to native promises, making it a robust choice for complex applications.

pify

Pify is a simple library that converts callback-based functions to promise-based ones. It is lightweight and easy to use, making it a good alternative for developers who need a straightforward solution without additional features.

README

wrap-promise

Small module to help support APIs that return a promise or use a callback.

Example

// my-method.js
var wrapPromise = require("wrap-promise");

function myMethod(arg) {
  return new Promise(function (resolve, reject) {
    doSomethingAsync(arg, function (err, response) {
      if (err) {
        reject(err);
        return;
      }

      resolve(response);
    });
  });
}

module.exports = wrapPromise(myMethod);

// my-app.js
var myMethod = require("./my-method");

myMethod("foo")
  .then(function (response) {
    // do something with response
  })
  .catch(function (err) {
    // handle error
  });

myMethod("foo", function (err, response) {
  if (err) {
    // handle error
    return;
  }

  // do something with response
});

Wrap All Methods on the Prototype

function MyObject() {}

MyObject.prototype.myAsyncMethod = function () {
  return new Promise(function (resolve, reject) {
    //
  });
};

MyObject.prototype.myOtherAsyncMethod = function () {
  return new Promise(function (resolve, reject) {
    //
  });
};

module.exports = wrapPromise.wrapPrototype(MyObject);

Static methods, sync methods on the prototype (though if you pass a function as the last argument of your sync method, you will get an error), and non-function properties on the prototype are ignored.

If there are certain methods you want ignored, you can pass an ignoreMethods array.

module.exports = wrapPromise.wrapPrototype(MyObject, {
  ignoreMethods: ["myMethodOnThePrototypeIDoNotWantTransformed"],
});

By default, wrapPrototype ignores methods that begin with an underscore. You can override this behavior by passing: transformPrivateMethods: true

module.exports = wrapPromise.wrapPrototype(MyObject, {
  transformPrivateMethods: true,
});