What is the once option in addEventListener in JavaScript?
addEventListener(type, handler, { once: true }) automatically removes the listener after the first call. This is useful for one-time events and avoids the need to manually call removeEventListener.
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More FAQs in Best Practices for Callbacks in JavaScript
Prefer promises or async/await for new code. Use named functions for removable listeners. Handle errors (Node.js convention). Keep nesting shallow. Remove listeners when done. Use event delegation for dynamic children. Avoid closing over large objects.
Use promises (chain .then calls) or async/await (flatten to synchronous-looking code). If you must use callbacks, extract them into named functions to keep nesting shallow. Or use a library like async.js for control flow.
Named functions. They can be removed with removeEventListener (you need the same reference), produce better stack traces, and are easier to debug. Anonymous functions cannot be removed and show as <anonymous> in traces.
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