dvikraman/repeat-until-async

repeat-until-async

Repeats the async function The library provides TypeScript definitions. No dependencies needed. Please be sure that your environment has Promise support (or has a polyfill).

Installation

$ npm install repeat-until-async

Usage

The simple use case is described below:

const repeatUntil = require('repeat-until-async');

const timeOfStart = Date.now();


// Wait for some async operation to end
repeatUntil(() => {
  const timePassed = Date.now() - timeOfStart;

  return (timePassed < 500)
      && (timePassed % 2 === 0)  // Some random stuff
          ? true
          : throw new Error('Async operation failed');
}, 600)
.then((result) => {
  // Here are the operations to be done after predicate
  console.log('Async operation succeeded, predicate result = ', result);
})
.catch((error) => {
  // Here are the operations to be done if predicate didn't succeed in the timeout
  console.log('Async operation failed: ', error);
});

async/await

The library is async/await compatible because it uses Promises/A+, so the example above could be rewritten:

const repeatUntil = require('repeat-until-async');

const timeOfStart = Date.now();


// Wait for some async operation to end
try {
  const result = await repeatUntil(() => {
    const timePassed = Date.now() - timeOfStart;

    return (timePassed < 500)
        && (timePassed % 2 === 0)  // Some random stuff
            ? true
            : throw new Error('Async operation failed');
  }, 600);

  // Here are the operations to be done after predicate
  console.log('Async operation succeeded, predicate result = ', result);
} catch (error) {
  // Here are the operations to be done if predicate didn't succeed in the timeout
  console.log('Async operation failed: ', error);
}

Supported arguments

/**
 * Waits for predicate to be truthy and resolves a Promise
 *
 * @param  predicate  Function  Predicate that checks the condition
 * @param  timeout  Number  Maximum wait interval, optional, 5000ms by default
 * @param  interval  Number  Wait interval, optional, 50ms by default
 * @return  Promise  Promise to return a callback result
 */
function repeatUntil(
    predicate: Function,
    timeout: Number = 5000,
    interval: Number = 50
): Promise;

Build

No building required, library is implemented with ES5 for better compatibility and shipped as is.

License

Library is shipped "as is" under MIT License.

Contributing

Feel free to contribute. Just raise ann issue, create a pull request covering it and don't forget to test everything properly.