How to Efficiently Add Key Values to Objects within an Array in JavaScript

Learn how to add new properties to objects in an array by checking values from another array in JavaScript. This simple guide provides step-by-step instructions.
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How to Efficiently Add Key Values to Objects within an Array in JavaScript

When working with JavaScript, you might encounter scenarios where you need to update properties in an array of objects based on values from another array. This is a common situation, especially when you want to enrich your data with additional attributes. In this guide, we'll explore how to accomplish this using a practical example.

The Problem

Let's say you have the following data structure:

Sample Data

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You wish to modify this array based on another array, which contains information regarding whether a person has canceled an event.

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Desired Output

The goal is to update array1 to include a new property isCanceled, based on the name key present in both arrays.

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The Solution

To achieve this, we can follow a more streamlined approach by converting array2 into an object for easier lookup. Here’s how to do it step-by-step:

Step 1: Convert array2 into a Lookup Object

Using the reduce method, we can transform array2 into a format that allows for quick lookups based on the name key.

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With the above code, arrCancel would look like this:

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Step 2: Update array1 with isCanceled Property

Now that we have a lookup object, we can utilize the map method to create a new array from array1, appending the isCanceled value based on the name property.

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Complete Code Example

Here’s the complete code showcasing both steps:

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Conclusion

By following these steps, you can efficiently add new properties to each object in an array based on data from another array. Using reduce for transformation and map for updating ensures your code remains clean and readable. This approach not only provides clarity but also significantly optimizes performance for larger datasets. Happy coding!