State Management Compared with Alternatives

There are a few ways to share common data across components in an LWC app. For example, you can set properties on child components to pass data into them from the parent. Events let you send data in the opposite direction. These simple solutions can be optimal for many apps, or a small set of related components that work together.

State management can work well in those situations too. However, it’s specifically designed to optimize data sharing for an app or collection of components that’s grown large and complex. For example, you don’t want to pass property values down chains of a dozen or more child components, or send events back up the same long hierarchy. A state manager is a “black box” that holds a set of related data values that are managed in a consistent way. Components in a shared subtree can access a state manager instance through the component hierarchy. You can also export a singleton state manager from a shared module, which gives all components that import it access to the same instance. Then, a component can use the state manager to read values managed elsewhere, or to perform safe, managed changes to the contents.

Developers can use LWC state management to address various challenges that arise from size and complexity.

Reduce Prop Drilling: In complex apps, passing data down through multiple layers of nested components (prop drilling) can become cumbersome and hard to maintain. State managers offer a way to access state in deeply nested children without explicitly passing props through every intermediate component.
Separate Data from Presentation: Separating the concerns of data retrieval, transformation, and business logic from the presentation logic of UI components that show that data leads to more maintainable and testable code.
Centralize State Logic: A state manager allows for the co-location of state definitions and the logic for updating that state. This makes it easier to understand and manage how data changes over time.
Improve Performance and Data Orchestration: By decoupling data loading from component rendering, state managers can enable scenarios like pre-fetching data before components render, potentially improving perceived performance. They also lay the groundwork for more advanced data coordination and optimization strategies.
Manage Complex State Interactions: For apps with intricate state dependencies and frequent updates, state managers provide a more robust and idiomatic way to handle these complexities compared to manual state handling or relying solely on @wire in many places.
Reusability: State logic encapsulated within a state manager can be reused across different parts of an app, or even in different apps.

LWC state management aims to provide an idiomatic way to manage state for larger collections of components (apps), making it more obvious how to retrieve, transform, distribute, and present data.