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  • License MIT

Waits until the given predicate function returns a truthy value, then resolves

Package Exports

  • async-wait-until

Readme

async-wait-until

A lightweight, zero-dependency library for waiting asynchronously until a specific condition is met. Works in any JavaScript environment that supports Promises, including older Node.js versions and browsers (with polyfills if necessary).

npm version npm downloads MIT License Maintainability

๐Ÿ“– Detailed Documentation

For detailed documentation, visit https://devlato.github.io/async-wait-until/


๐Ÿš€ Installation

Install using npm:

npm install async-wait-until

The library includes UMD, CommonJS, and ESM bundles, so you can use it in any environment.

import { waitUntil } from 'async-wait-until';

// Example: Wait for an element to appear
await waitUntil(() => document.querySelector('#target') !== null);

๐Ÿ› ๏ธ How to Use

Basic Example: Wait for a DOM Element

import { waitUntil } from 'async-wait-until';

const waitForElement = async () => {
  // Wait for an element with the ID "target" to appear
  const element = await waitUntil(() => document.querySelector('#target'), { timeout: 5000 });
  console.log('Element found:', element);
};

waitForElement();

Handling Timeouts

If the condition is not met within the timeout, a TimeoutError is thrown.

import { waitUntil, TimeoutError } from 'async-wait-until';

const waitForElement = async () => {
  try {
    const element = await waitUntil(() => document.querySelector('#target'), { timeout: 5000 });
    console.log('Element found:', element);
  } catch (error) {
    if (error instanceof TimeoutError) {
      console.error('Timeout: Element not found');
    } else {
      console.error('Unexpected error:', error);
    }
  }
};

waitForElement();

๐Ÿ“š API

waitUntil(predicate, options)

Waits for the predicate function to return a truthy value and resolves with that value.

Parameters:

Name Type Required Default Description
predicate Function โœ… Yes - A function that returns a truthy value (or a Promise for one).
options.timeout number ๐Ÿšซ No 5000 ms Maximum wait time before throwing TimeoutError. Use WAIT_FOREVER for no timeout.
options.intervalBetweenAttempts number ๐Ÿšซ No 50 ms Interval between predicate evaluations.

๐Ÿ’ก Recipes

Wait Indefinitely

Use WAIT_FOREVER to wait without a timeout:

import { waitUntil, WAIT_FOREVER } from 'async-wait-until';

await waitUntil(() => someCondition, { timeout: WAIT_FOREVER });

Adjust Retry Interval

Change how often the predicate is evaluated:

await waitUntil(() => someCondition, { intervalBetweenAttempts: 1000 }); // Check every 1 second

๐Ÿงช Development and Testing

Contributions are welcome! To contribute:

  1. Fork and clone the repository.
  2. Install dependencies: npm install.
  3. Use the following commands:
  • Run Tests: npm test
  • Lint Code: npm run lint
  • Format Code: npm run format
  • Build Library: npm run build
  • Generate Docs: npm run docs