If you have say twenty thousand rows to render, you probably don’t want to fetch all that data at once and you especially don’t want to render all those rows on page load. This talk is about how to render only the rows you need and how to just-in-time load data for those rows.

On the frontend, this means “windowing” or “virtualizing”: only rendering enough rows to fill the view port, with maybe just a few extra.

On the backend, it means just-in-time load chunks of row data from the server as new rows scroll into view.

The examples will be using a Node.js server with a React frontend. However the concepts of windowing and just-in-time data loading are applicable to any tech stack.