Filtering Arrays in TypeScript: A Complete Guide

Описание: Learn how to filter two arrays in TypeScript based on matching IDs with practical examples. Ideal for beginners tackling array manipulation!
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This video is based on the question https://stackoverflow.com/q/66179762/ asked by the user 'cdub' ( https://stackoverflow.com/u/665557/ ) and on the answer https://stackoverflow.com/a/66179854/ provided by the user 'Terry' ( https://stackoverflow.com/u/395910/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Filtering Arrays in TypeScript: A Complete Guide

In the world of programming, especially in JavaScript and TypeScript, working with arrays is a fundamental skill. One common task developers encounter is filtering arrays based on certain criteria. If you've ever faced a scenario where you need to determine which elements from one array exist in another based on specific properties, you're in the right place!

The Problem

Suppose you have two arrays, each containing objects with a property called myId. You want to extract objects from the first array that are present in the second, based solely on matching myId values.

The Sample Data

Let's take a look at the two arrays:

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Our goal is to create a new array that contains objects from array1 where the property myId matches with any object from array2.

The Solution

To solve this problem efficiently, we can follow a structured approach:

Step 1: Collect Identifiers from array2

First, we need to gather all myId values from array2. Using a Set is advantageous because it will automatically handle duplicate values for us.

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Step 2: Filter array1

Next, we filter array1 using the collected IDs. The Array.prototype.filter method allows us to retain only those items that meet the specified criteria:

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Step 3: Output the Result

Finally, we can log the resulting array to see the filtered objects:

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The Complete Code

Putting it all together, the complete code looks like this:

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Conclusion

In conclusion, filtering arrays based on shared properties is a powerful technique in TypeScript. By utilizing methods like map() and filter(), we can efficiently work with data to achieve the desired results.

Feel free to try out this technique in your projects, and don’t hesitate to explore further! Happy coding!