Скачать или смотреть How to Properly Map Data Inside a Map in JavaScript and React

Learn how to effectively map over data in React to display values in a structured table format with this easy-to-follow guide.
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This video is based on the question https://stackoverflow.com/q/70285797/ asked by the user 'Yaniv Suriyano' ( https://stackoverflow.com/u/8526311/ ) and on the answer https://stackoverflow.com/a/70285889/ provided by the user 'Ivo' ( https://stackoverflow.com/u/6270118/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Properly Map Data Inside a Map in JavaScript and React

When developing applications using React, one common task you'll often face is displaying data in a user-friendly way—like in a table format. You might find yourself asking, "How do I show specific fields of data from an array of objects?" In this guide, we’ll tackle how to efficiently map over an array of data to extract and display the desired values.

Understanding the Problem

Consider the following JavaScript data structure:

[[See Video to Reveal this Text or Code Snippet]]

You also have a configuration object that specifies which fields you want to display:

[[See Video to Reveal this Text or Code Snippet]]

Your goal is to display the name property of each object in the data array within a table format. However, you might encounter an issue when using the .map() function, leading to confusion and frustration, as you might find it doesn't work as expected.

The Solution: Fixing the Mapping Logic

Step-by-Step Breakdown

Identify the Configuration Key: The configuration you've set up uses the key fieldToShow. The mistake in your mapping lies in trying to access a non-existent field property.

Adjust the Mapping Logic: To resolve the issue, you need to change how you access the properties of the objects being mapped. Specifically, you should access fieldToShow instead of field. Here's how your mapping should look:

Instead of:

[[See Video to Reveal this Text or Code Snippet]]

Change it to:

[[See Video to Reveal this Text or Code Snippet]]

Complete Example

Here’s how a complete implementation would look:

[[See Video to Reveal this Text or Code Snippet]]

Key Considerations

Ensuring Key Uniqueness: When rendering lists in React, make sure each child has a unique key prop. This helps React optimize the rendering process.

Data Structure Consistency: Ensure that the data structure you are mapping over is consistent with the configuration object to avoid runtime errors.

Conclusion

In summary, when working with data mapping in React, always be mindful of the keys you are accessing. Adjusting the property you use in your mapping function can turn a frustrating debugging session into a smooth rendering of your desired data. With the changes outlined above, you should be able to dynamically display any property specified in your configuration.

Do you have questions or experiences you'd like to share regarding data mapping in React? Feel free to comment below!