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waitFor ​

Problem ​

You need to poll until a condition becomes true — for example waiting for a DOM element to appear, a flag to be set, or a resource to become available.

Solution ​

Use waitFor(condition, options?) to poll condition until it returns true or the timeout fires.

ts
import { waitFor } from '@vielzeug/arsenal';

// Wait for a DOM element
await waitFor(() => document.querySelector('#app') !== null, { timeout: 3_000 });

// Wait for a flag
let ready = false;
setTimeout(() => {
  ready = true;
}, 500);
await waitFor(() => ready);

With AbortSignal ​

ts
import { waitFor } from '@vielzeug/arsenal';

const controller = new AbortController();
setTimeout(() => controller.abort(), 1_000);

await waitFor(() => isServiceReady(), {
  timeout: 5_000,
  signal: controller.signal,
});

Pitfalls ​

  • Throws a TimeoutError (or AbortError) when the condition never becomes true within the timeout or the signal fires.
  • The condition function is called on a polling interval — avoid expensive operations inside it.