Description

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Advanced · 12 min

Bounded retries

Retry a known temporary failure while keeping attempts finite.

Set a clear bound

A retry loop needs a maximum number of attempts and a final failure path. Retry only failures the operation identifies as temporary.

let calls = 0;
async function load() { calls += 1; if (calls < 2) throw new Error("Temporary"); return "Ready"; }
let result;
for (let attempt = 1; attempt <= 2; attempt += 1) {
  try { result = await load(); break; }
  catch (error) { if (attempt === 2) throw error; }
}
console.log(result);
console.log(calls);

Output

Ready
2

Preserve permanent failures

Invalid input should not be retried. In network applications, also consider backoff, cancellation, and whether repeating the operation is safe.

async function load() { const error = new Error("Invalid input"); error.retryable = false; throw error; }
try { await load(); } catch (error) { console.log(error.retryable ? "Retry" : "Stop"); }

Output

Stop

Put it into practice

  1. Predict each result before running the example.
  2. Complete the coding task, then explain why your solution works.

Try it yourself

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Allow the second attempt

The local operation fails once, then succeeds. Let it try at most twice and display the result.

Practice