Redux与React渲染疑问：请求完成后传相同Posts组件是否重渲染？

Problem Statement #

We have this sequence of actions:

• Fetch some posts
• Store them in the Redux Store
• Display them on a page
• Navigate to another page
• Navigate back

After these steps, the Redux Store already holds a list of posts. The question is: When the request completes and the component receives exactly the same posts list content as props, will React re-render the list?

Answer #

Great question! Let’s break this down clearly:

First, the core takeaway: By default, yes, it will re-render—but you can optimize to prevent this unnecessary update.

1. How React’s Re-Render Logic Works

React determines whether to re-render a component by comparing prop/state references, not the actual content of the values. Here’s how it applies to your scenario:

• If your Redux reducer returns a new array reference (like using [...state.posts], posts.map(), or any method that creates a fresh array) even if the content matches the old list, React will see the prop as "changed" and trigger a re-render.
• If your reducer returns the original array reference (e.g., return state.posts without creating a new array), React won’t re-render because the prop reference hasn’t shifted. That said, this is not recommended in Redux—reducers must return new state references to properly trigger subscription updates for connected components.

2. Optimizations to Skip Unnecessary Re-Renders

If you want to avoid re-renders when the post content is identical, here are reliable approaches:

• Wrap your list component with React.memo(): This utility does a shallow comparison of props. If the new props are shallowly equal to the old ones (even if references differ but content matches), it skips the re-render.
• Use memoized selectors with Reselect: Create a selector that only returns a new array reference when the actual post data changes. This way, connected components only receive updated props when there’s real content changes, not redundant state reference updates.
• Memoize individual list items: Wrap each post’s child component with React.memo() too. Pair this with stable key props, and React’s diff algorithm will only update DOM elements that actually change—even if the parent list component does re-render.

内容的提问来源于stack exchange，提问作者Src