What are the Different Retry Patterns for Promise-Based Operations in JavaScript?

Retry Patterns for Promise-Based Operations

Promises provide a convenient way to handle asynchronous operations in JavaScript. However, sometimes it is necessary to retry operations multiple times or until a specific condition is met.

1. Retrying until Promise Resolves

To continuously retry an operation until it resolves, use a delay between retries and a maximum number of retries. This can be achieved using a for loop and .catch() chaining:

<code class="js">for (var i = 0; i < maxRetries; i++) {
  p = p.catch(attempt).catch(rejectDelay);
}</code>

2. Retrying until Condition Meets

To retry an operation until a condition is met on the result, use a .then() chain to check the condition and a .catch() chain to handle failures:

<code class="js">for (var i = 0; i < maxRetries; i++) {
  p = p.catch(attempt).then(test);
}</code>

3. Memory-Efficient Dynamic Retry Pattern

For a dynamic retry mechanism with unlimited retries and a specified delay, use the .catch() chain approach:

<code class="js">var p = Promise.reject();
while (true) {
  p = p.catch(attempt).catch(rejectDelay);
  // Break out of the loop if the condition is met.
  if (conditionMet) break;
}</code>

Note:

• The .catch() chain approach for retries has limitations regarding the maximum number of attempts and memory consumption.
• For complex retry scenarios, it is recommended to use recursive solutions or purpose-built retrying libraries.

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