JavaScript

Queue (Async Task Queue)

by @admin

12h ago

Apr 28, 2026

Public

A serialised async task queue that executes queued async functions one at a time, in order. Useful for sequencing operations that must not run concurrently (file writes, ordered API mutations, step-by-step wizards). add() returns a Promise that resolves/rejects when that specific task completes.

JavaScript

function createQueue() {
  let tail = Promise.resolve();
  return {
    add(task) {
      const result = tail.then(() => task());
      tail = result.catch(() => {}); // keep queue running on error
      return result;
    },
  };
}

// Usage
const q = createQueue();

q.add(() => fetch('/api/step1').then((r) => r.json())).then(console.log);
q.add(() => fetch('/api/step2').then((r) => r.json())).then(console.log);
// step2 only starts after step1 finishes

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