Retry

When a function may succeed after some attempts, you might need a retry logic - keep trying the function until it succeeds, or after a certain number of attempts. You want some kind of waiting period between each attempt, eg to wait for a network connection.

This can be achieved using Flow.retryFunction .

In the example, we will try up to five times to run the async function doSomething, starting with 1 second delay if it fails. This time gets longer and longer with each attempt.

import { retry } from "https://unpkg.com/ixfx/dist/flow.js"

const doSomething = () => {
  // If this function throws an error or returns undefined,
  // it's assumed to have failed

  // for it to succeed it has to return a value
}

const result = await retryFunction(doSomething, { limitAttempts: 5, startAt: 1000 });
if (result.success) {
  // Yay result.value will contain the result of `doSomething`
} else {
  // result.message tells why it failed
}

See also:

• Flow.waitFor - call a function and be notified if it doesn’t finish within a certain time

Advanced

Options :

• taskValueFallback: option can provide a value if the task ultimately fails
• abort: an abort signal to cancel waiting
• predelayMs: time to wait before first attempt
• limitAttempts: total number of times to retry
• limitValue: limit for how many milliseconds to wait
• startAt: starting milliseconds