digitwin/node_modules/promise-retry/README.md

node-promise-retry

Retries a function that returns a promise, leveraging the power of the retry module to the promises world.

There's already some modules that are able to retry functions that return promises but they were rather difficult to use or do not offer an easy way to do conditional retries.

Installation

$ npm install promise-retry

Usage

promiseRetry(fn, [options])

Calls fn until the returned promise ends up fulfilled or rejected with an error different than a retry error.
The options argument is an object which maps to the retry module options:

• retries: The maximum amount of times to retry the operation. Default is 10.
• factor: The exponential factor to use. Default is 2.
• minTimeout: The number of milliseconds before starting the first retry. Default is 1000.
• maxTimeout: The maximum number of milliseconds between two retries. Default is Infinity.
• randomize: Randomizes the timeouts by multiplying with a factor between 1 to 2. Default is false.

The fn function will receive a retry function as its first argument that should be called with an error whenever you want to retry fn. The retry function will always throw an error.
If there are retries left, it will throw a special retry error that will be handled internally to call fn again. If there are no retries left, it will throw the actual error passed to it.

If you prefer, you can pass the options first using the alternative function signature promiseRetry([options], fn).

Example

var promiseRetry = require('promise-retry');

// Simple example
promiseRetry(function (retry, number) {
    console.log('attempt number', number);

    return doSomething()
    .catch(retry);
})
.then(function (value) {
    // ..
}, function (err) {
    // ..
});

// Conditional example
promiseRetry(function (retry, number) {
    console.log('attempt number', number);

    return doSomething()
    .catch(function (err) {
        if (err.code === 'ETIMEDOUT') {
            retry(err);
        }

        throw err;
    });
})
.then(function (value) {
    // ..
}, function (err) {
    // ..
});

Tests

$ npm test

License

Released under the MIT License.