The key to maintaining maintainability in large React projects is clear structure, division of responsibilities and collaborative support, which mainly includes three points: First, organize the file structure according to functions, and centralize components, styles, services and other files based on functional modules to facilitate modification, isolation and reuse; Second, adopt appropriate state management strategies, such as Redux Toolkit or Context useReducer, centrally manage state logic and avoid unnecessary updates; Third, pay attention to component design, follow a single responsibility, control the number of props, extract general logic to custom hooks, and improve encapsulation and reusability.

Maintaining maintainability in large React projects is a clear structure, a reasonable division of responsibilities, and support for teamwork. There is no unified standard answer, but there are some proven patterns and habits that can significantly improve the long-term maintainability of a project.

Organization of file structure by function (Feature-based Structure)

Instead of splitting directories by type (such as components, containers, actions), it is better to organize the code in units of functional modules. For example, a todos/ directory can have a todos/ directory containing components, styles, services, tests and other files related to the function.

The benefits of doing this are:

• When modifying a function, you do not need to switch back and forth between multiple directories.
• Easier isolating and reusing functional modules
• Newcomers can understand code structure more easily

For example, a feature folder might look like this:

 /src
  /features
    /todos
      TodosList.jsx
      TodoItem.jsx
      todosSlice.js
      todosService.js
      index.js

This structure is especially suitable for medium and large projects, and can better support lazy loading and code segmentation.

Use state management strategies to avoid over-necking

React's local state is OK for small components, but once the project gets bigger, frequent props passes will make the component tree bloated and difficult to maintain. At this time, a status management plan needs to be introduced.

The current mainstream choice is Redux Toolkit or Context useReducer. The following points can be considered when choosing:

• Is the team familiar with Redux? If you are not familiar with it, Toolkit is a good entry-level choice
• Do you need more states to share globally? If there are many, Redux is more suitable
• Do you prefer to reduce dependencies? Context is a native solution, but it is easy to be confused in complex scenarios

No matter which method you choose, it is recommended:

• Centrally manage state logic to avoid dispersing among multiple components
• Try to update status through action or dispatch functions to facilitate tracking changes
• Avoid unnecessary status updates and use memoization (useMemo, useCallback) reasonably

Component design should focus on packaging and reuse

Components are the core unit of React, and good component design directly affects the maintainability of the project.

Several practical suggestions:

• Single Responsibility: Each component does only one thing, and complex components can be split into multiple subcomponents
• Controlling the number of props: Too many props will increase understanding and maintenance costs, you can consider context or state management alternatives
• Try to make the components "silly" as possible: UI layer components focus on display, and business logic is handed over to container components or hooks
• Extract general logic to custom hooks: such as form processing, data acquisition, animation control, etc.

To give a simple example, if you find that multiple places need to process form input, you can write a useForm hook to handle verification, submission, error prompts and other logic uniformly, instead of repeating similar useState and useEffect in each component.

Basically that's it.
The design of React project structure is not achieved overnight, but a process of continuous evolution as the project develops. The key is to establish specifications as soon as possible and continuously optimize during the development process.

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