FrontendHaltReact·Intermediate·Conceptual·1 min read
Why is a file input always uncontrolled?
Short interview answer
For security reasons, JavaScript cannot programmatically set a file input's value to an arbitrary file path — the browser only allows the user's own file-picker interaction to set it, so React can only read the selected file via a ref or the change event, never drive it via a value prop.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.