Скачать или смотреть How to Merge Two JavaScript Objects After Filtering

Learn how to merge two JavaScript objects, filtering out unwanted entries for a clean and efficient data structure. Perfect for developers seeking to optimize their data management.
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This video is based on the question https://stackoverflow.com/q/74826303/ asked by the user 'Shibbir' ( https://stackoverflow.com/u/1091439/ ) and on the answer https://stackoverflow.com/a/74826569/ provided by the user 'Neha Soni' ( https://stackoverflow.com/u/11834856/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Challenge of Merging Data in JavaScript

When working with arrays of objects in JavaScript, you often need to filter, merge, or transform data based on specific criteria. A common scenario is to filter out certain items and then merge the relevant data from different sources while avoiding duplicates. In this guide, we'll explore how to merge two object arrays in JavaScript after applying a filtering condition.

Let's grasp this with a hands-on example explained step by step.

The Initial Data

We start with two arrays of objects:

Old Data: This array contains items we want to filter and renew.

New Data: This array contains potentially new items that need to be added, provided they don't duplicate any existing entries from our filtered old data.

Old Data Example

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New Data Example

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Filtering the Old Data

Our goal is to filter the old_data array so that we exclude any items where the text property equals "do_not_import". We can achieve this with the filter method:

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

Result of Filtering

After applying the filter, our filter_data array looks like this:

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

Merging the Filtered Data with New Data

The next step is to merge the filtered results with the newData, ensuring that we do not include any duplicates based on the value key. Here's how to proceed:

Create a Set from Filtered Values: We’ll create a Set of the value properties from the filter_data, which allows for faster look-ups when checking against the newData.

Filter New Data: We’ll use the filter method again to only include items from newData where the value does not exist in the Set.

Combine Both Arrays: Finally, we’ll merge the filtered arrays of filter_data and the filtered newData.

The Code to Merge:

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

The Merged Result

The final output after merging will be:

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

Conclusion

Merging and filtering data arrays in JavaScript can be straightforward with the use of built-in array methods such as filter and map. By using these tools properly, you can create efficient and clean data structures. This technique not only helps in avoiding duplication, but also ensures that you're only working with the relevant data.

For developers looking to manage their data effectively, mastering these array manipulations can lead to cleaner code and better performance. Happy coding!