What is a prevRowCountState in mui-data-grid?

Question

Server pagination, I understand the logic but can't figure out how does the grid know the value of prevRowCountState. Is it a undocumented thing, prefix a const/property with prev then the grid knows it's for the previous value?

const [rowCountState, setRowCountState] = React.useState(rowCount);
React.useEffect(() => {
  setRowCountState((prevRowCountState) =>
    rowCount !== undefined ? rowCount : prevRowCountState,
  );
}, [rowCount, setRowCountState]);

<DataGrid rowCount={rowCountState} />;

Answer 1

set<Something> is action of setState method for Something. When supplying an argument in a form of function such as set<Something>((whatever)=> {...});, whatever is the previous state of something.

References:

• React's State, starting "To fix it, use a second form of setState()..."
• Geek to Geek, example 4,