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Get the Indexes of Filtered Array Items in JavaScript

Learn how to effectively retrieve the `indexes` of filtered array items in JavaScript, enhancing your programming skills with easy-to-understand examples. --- This video is based on the question https://stackoverflow.com/q/72235314/ asked by the user 'NewProgrammer' ( https://stackoverflow.com/u/16900056/ ) and on the answer https://stackoverflow.com/a/72235366/ provided by the user 'Юрий Копоть' ( https://stackoverflow.com/u/4275277/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How can I get the indexes of a filtered array items Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- How to Get the Indexes of Filtered Array Items in JavaScript When working with arrays in JavaScript, you often find yourself needing not just the items that meet certain criteria, but also their original positions in the array. This can be particularly useful for tasks like tracking items or modifying entries based on their indices. In this guide, we'll take a close look at a practical situation where you filter an array, and we'll explore how to retrieve the indexes of the filtered items using a straightforward approach. The Problem at Hand Let's say you have an array of date strings representing different months and years, and you want to filter those to find only the items from the year 2022: [[See Video to Reveal this Text or Code Snippet]] You apply a filter to extract just the 2022 values: [[See Video to Reveal this Text or Code Snippet]] This results in the following filtered array: [[See Video to Reveal this Text or Code Snippet]] However, you also need to know the indexes of these filtered items within the original array, which should look like this: [[See Video to Reveal this Text or Code Snippet]] So, how do you achieve this? Let’s dive into the solution. Step-by-Step Solution To obtain both the filtered items and their corresponding indexes, you can leverage the filter method, augmented with an index parameter. Here’s how you can do it: 1. Initialize an Array for Indexes First, you'll need to create an empty array that will hold the indexes of the filtered items: [[See Video to Reveal this Text or Code Snippet]] 2. Use the Filter Method with an Index Parameter Now, apply the filter method on your array, utilizing the second parameter (indx) to capture the index of each element during filtering: [[See Video to Reveal this Text or Code Snippet]] Complete Code Snippet Here is the complete code that combines the above steps: [[See Video to Reveal this Text or Code Snippet]] 3. Understanding the Output When you run this code, you will get two outputs: The filter variable contains the filtered array items: ['2022-05', '2022-04', '2022-02']. The index variable contains the respective indexes of those items in the original array: [0, 2, 3]. Conclusion By following this method, you can efficiently retrieve both the filtered items and their indexes from an array in JavaScript. This approach not only provides clarity to your code but also enhances its functionality, making it easier to handle more complex data manipulations in the future. Happy coding!