Candidates should understand how to optimize event handling, especially in large DOM structures.
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Understand the problem
eventsdomperformanceevent bubbling
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Study the solution
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Read the code
one listener for a whole list (DOM)
// Delegation: listen on the parent, not each <li>
document.querySelector('#list').addEventListener('click', (e) => {
const li = e.target.closest('li');
if (li) console.log('clicked item:', li.dataset.id);
});
// Works even for <li> added later — no rebinding needed.05
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