Redux saga is a middleware between an application and redux store, that is handled by redux actions. This means, it can listen to actions, intercept actions it is interested in and replace them with other actions. This may be useful for plenty of things. In particular, using sagas you can keep your components as simple as possible and move all the logic to sagas.
When you start working with Redux saga, it seems quite natural to write sagas that describe behavior of a single component or a single page. And it works fine in simple applications that have two or three pages and everything is loaded synchronously. But when a project grows, this may lead you to a mess in sagas department, where sagas don’t have clear purposes and duplicate each other in many ways. It will be difficult to manage, debug and make even small changes.
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