TryLoop

Simple library for retrying operations, it supports multiple backoff strategies.

Install

npm install --save tryloop

Usage

You'll have to provide the options.fn function, which will be the operation to retry.

• If the function throws, TryLoop will throw.
• If the function returns undefined, or a Promise which resolves to undefined, the operation will be retried.
• If the function returns any other value, or a Promise which resolves to any other value, TryLoop will return a Promise to that value.
• If the function can't be retried any longer, e.g. maybe the timeout run out or we hit the max retries limit, TryLoop will return undefined.

There are multiple backoff/retry strategies implemented, each with its own particular retry logic.

In general you're going to use the library like this:

import tryloop from 'tryloop';

const instance = tryloop.__strategy_name__ ({
  fn: () => {}, // Operation to retry
  // Other options...
});

const result = await instance.start ();

// instance.stop (); // Stops retrying the operation
// instance.cancel (); // Just an alias for "stop"

Strategies

Linear

The linear strategy retries the operation after a fixed interval.

These are the accepted options:

type Options = {
  fn: () => any, // Operation to retry
  timeout: number, // Return undefined after this timeout
  tries: number, // Return undefined after this number of tries
  interval: number // Fixed interval between retries
};

You can use it like so:

import tryloop from 'tryloop';

const instance = tryloop.linear ({
  fn: () => {}, // Operation to retry
  timeout: 10000, // Time out after 10s
  tries: 100, // Not more than 100 tries
  interval: 100 // Wait 100ms between retries
});

const value = await instance.start ();

Idle

The idle strategy retries the operation by calling requestIdleCallback.

These are the accepted options:

type Options = {
  fn: () => any, // Operation to retry
  timeout: number, // Return undefined after this timeout
  tries: number // Return undefined after this number of tries
};

You can use it like so:

import tryloop from 'tryloop';

const instance = tryloop.idle ({
  fn: () => {}, // Operation to retry
  timeout: 10000, // Time out after 10s
  tries: 100 // Not more than 100 tries
});

const value = await instance.start ();

Exponential

The exponential strategy retries the operation with exponentially increasing intervals.

These are the accepted options:

type Options = {
  fn: () => any, // Operation to retry
  timeout: number, // Return undefined after this timeout
  tries: number, // Return undefined after this number of tries
  factor: number, // Base factor which will be exponentiated after each try
  minInterval: number, // Minimum interval between retries, also starting interval
  maxInterval: number // Maximum interval between retries
};

You can use it like so:

import tryloop from 'tryloop';

const instance = tryloop.exponential ({
  fn: () => {}, // Operation to retry
  timeout: 10000, // Time out after 10s
  tries: 100, // Not more than 100 tries
  factor: 2, // Base factor
  minInterval: 1, // Start with 1ms
  maxInterval: 1000 // No more than 1s between retries
});

const value = await instance.start ();

requestAnimationFrame

The idle strategy retries the operation by calling requestAnimationFrame.

These are the accepted options:

type Options = {
  fn: () => any, // Operation to retry
  timeout: number, // Return undefined after this timeout
  tries: number // Return undefined after this number of tries
};

You can use it like so:

import tryloop from 'tryloop';

const instance = tryloop.raf ({
  fn: () => {}, // Operation to retry
  timeout: 10000, // Time out after 10s
  tries: 100 // Not more than 100 tries
});

const value = await instance.start ();

Random

The random strategy retries the operation using intervals randomly calculated between the min and the max.

These are the accepted options:

type Options = {
  fn: () => any, // Operation to retry
  timeout: number, // Return undefined after this timeout
  tries: number, // Return undefined after this number of tries
  minInterval: number, // Minimum interval between retries
  maxInterval: number // Maximum interval between retries
};

You can use it like so:

import tryloop from 'tryloop';

const instance = tryloop.random ({
  fn: () => {}, // Operation to retry
  timeout: 10000, // Time out after 10s
  tries: 100, // Not more than 100 tries
  minInterval: 1, // Randomly pick an interval >= 1ms
  maxInterval: 1000 // Randomly pick an interval <= 1ms
});

const value = await instance.start ();

License

MIT © Fabio Spampinato