What is a SyntheticEvent in React?
Quick answer
A cross-browser wrapper around the native DOM event with the same API. React uses it for consistent event behaviour across browsers.
In detail
React normalises events into SyntheticEvent objects so e.preventDefault(), e.target, etc. work identically everywhere. In React 17+ events are attached to the root container (not document) via delegation. You access the native event with e.nativeEvent if needed.
<form onSubmit={e => { e.preventDefault(); submit(); }}>
<button>Go</button>
</form>Why interviewers ask this: Checks understanding of React's event system.
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