waitup

Waitup - Delays and retries within Promise chains

Wait up for whatever.

Waitup provides delays and retries within Promise chains.

Installation

Waitup was written for Node.js 4+.

npm install --save waitup

Usage

There are several ways of using Waitup.

Simple Delays

Waitup can be used to introduce a delay before continuing within a Promise chain.

let waitup = require('waitup');

// Delay is in milliseconds, result is a Promise
waitup(5000)
  .then(() => {
    console.log('Waited approximately 5 seconds...')

    // Alternative method of configuring delay
    return waitup({
      delay: 2500
    });
  })
  .then(() => {
    console.log('Waited approximately 2.5 seconds this time...');
  });

Calling waitup returns a Promise. The default delay is 1 second (1000 milliseconds).

Wait Up For Completion

Waitup can also be configured to wait for the completion of an operation. A callback can be provided to waitup's for option. This callback accepts a single argument for the waitee. When the operation is considered complete, return the value of waitee.done(). An optional result can be provided to waitee.done() to forward to the resolved promise.

// Set someResult to true in approximately 5 seconds
let someResult = false;
setTimeout(() => someResult = true, 5000);

// Check every 0.5 seconds for operation to complete
waitup({
  for: waitee => {
    if (someResult === true) {
      return waitee.done('example result');
    }

    console.log('someResult not true yet');
  },
  delay: 500
})
  .then(exampleResult => {
    console.log('Waitee is done waiting!');
    console.log(`Result: ${exampleResult}`);
  });

Additionally, a number of retries can be configured before rejection. Set the number of allowable retries to waitup's retries option.

let someResult = false;

// Check every 0.5 seconds for someResult to change to true
waitup({
  for: waitee => {
    if (someResult === true) {
      return waitee.done();
    }

    console.log('someResult not true yet');
  },
  retries: 5,
  delay: 500
})
  .then(() => {
    console.log('This will never succeed...');
  })
  .catch(error => {
    console.log(error.stack);
  });

If retries are not configured, or if the waitee.done() value is never returned, the application could run indefinitely.

Examples

See more examples in the examples directory.

Logo

Waitup's initial logo was designed by scorpion6 on Fiverr. Font used is Lato Light.

License

This software is licensed under the MIT License. View the license.

Copyright © 2015 Michael K. Squires