promise-holder

Overview

promise-holder is a javascript/typescript package designed to simplify the handling of promises in your application. It provides a set of utilities and functions to streamline the creation, resolution, and rejection of promises, making asynchronous code management more efficient.

Installation

Install the package using npm:

npm install promise-holder

TL; DR

import PromiseHolder from 'promise-holder';

function waitTimeout() {
  const promise = new PromiseHolder();

  setTimeout(
    () => {
      // You can resolve you promise whenever you want
      promise.resolve(123);
      console.log('resolved');
    },
    100,
  )

  console.log('before await');

  // Promise can be awaited like regular promise
  const value = await promise;

  console.log('awaited', value);
}

await waitTImeout();
// before await
// resolved
// awaited 123

API

new PromiseHolder()

To create a promise, simply instantiate PromiseHolder class.

import PromiseHolder from 'promise-holder';

const promise = new PromiseHolder();

promise.then(onFulfilled, onRejected)

See Promise.then documentation.

promise.catch(onRejected)

See Promise.catch documentation.

promise.createdAt: date

Date at which the promise has been created

promise.resolve(value)

Callback to call to resolve the promise:

const promise = new PromiseHolder();

promise.resolve(123);

promise.then(
  (value) => {
    console.log(value); // 123
  }
);

Notice: calling the resolve method several more times will have no effect : only the first call will be resolved by the promise.

promise.reject(reason)

Callback to call to reject the promise:

const promise = new PromiseHolder();

const err = new Error('Promise rejected');
promise.reject(err);

promise.catch(
  (err) => {
    console.log(err.message); // Promise rejected
  }
);

Notice: calling the reject method several more times will have no effect : only the first call will be used as promise rejection reason.

promise.nodeCallback(err, value)

Use this method as node callback to resolve or reject the promise.

const PromiseHolder = require('promise-holder');
const fs = require('fs');

const promise = new PromiseHolder();
fs.readFile('myFile.txt', promise.nodeCallback);

promise.then(
  (file) => {
    console.log(file); // myFile.txt content
  },
);

promise.onTime(timeout): Promise<boolean>

Return a promise that indicate if the promiseHolder has been resolved/rejected before the indicated duration:

• If the PromiseHolder has been resolved before the duration, then the promise resolve true. It will be resolved the moment the PromiseHolder has been fulfilled
• If the PromiseHolder hasn't been resolved in time, the promise resolve false at the end of the duration.

const PromiseHolder = require('promise-holder');
const fs = require('fs');

const promise = new PromiseHolder();
promise.inTime(1000).then(
  (inTime) => {
    console.log('inTime', inTime); // inTime false
  }
)