react.dev/content/docs/controlled-input-null-value.md

id, title, permalink

id	title	permalink
controlled-input-null-value	Controlled input null value	docs/controlled-input-null-value.html

Specifying the value prop on a controlled component prevents the user from changing the input unless you desire so.

You might have run into a problem where value is specified, but the input can still be changed without consent. In this case, you might have accidentally set value to undefined or null.

For example, this code shows this phenomenon; after a second, the text becomes editable.

ReactDOM.render(<input value="hi" />, mountNode);

setTimeout(function() {
  ReactDOM.render(<input value={null} />, mountNode);
}, 1000);