"Concurrent Mode is a set of new features that help React apps stay responsive and gracefully adjust to the user's device capabilities and network speed." — React Docs
Caution:
This page describes experimental features that are not yet available in a stable release. Don’t rely on experimental builds of React in production apps. These features may change significantly and without a warning before they become a part of React.
This documentation is aimed at early adopters and people who are curious. If you’re new to React, don’t worry about these features — you don’t need to learn them right now.
Common data-fetching approaches in React
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Fetch-on-render (for example, fetch in useEffect): Start rendering components. Each of these components may trigger data fetching in their effects and lifecycle methods. This approach often leads to “waterfalls”.
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Fetch-then-render (for example, Relay without Suspense): Start fetching all the data for the next screen as early as possible. When the data is ready, render the new screen. We can’t do anything until the data arrives.
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Render-as-you-fetch (for example, Relay with Suspense): Start fetching all the required data for the next screen as early as possible, and start rendering the new screen immediately — before we get a network response. As data streams in, React retries rendering components that still need data until they’re all ready.
README.md a work in progress...