Скачать или смотреть How to Get Unknown Children of a Node from a JSON in JavaScript

In this guide, we will explore how to extract child nodes from a JSON object in JavaScript without knowing their names, using `forEach` loops effectively.
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This video is based on the question https://stackoverflow.com/q/70865440/ asked by the user 'Raymond Eiber' ( https://stackoverflow.com/u/6778858/ ) and on the answer https://stackoverflow.com/a/70865965/ provided by the user 'Serge' ( https://stackoverflow.com/u/11392290/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

If you're building a web tool that needs to extract specific metrics from a JSON object – like the Core Web Vitals metrics – you might find yourself needing to access child nodes that are dynamic and unknown. How do you achieve this using JavaScript?

Today, we'll dive into this problem and provide a straightforward solution that utilizes the power of JavaScript’s built-in methods combined with JSON data structure.

The Challenge

Imagine you have the following JSON structure:

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

You want to access the values of p75 for multiple metrics without needing to specify their names. This requires a savvy approach to navigating through the JSON structure.

Solution

Step 1: Preparing Your Data

To begin, we have a JSON object that contains the metrics data as shown above. The first step is to ensure that you have the necessary data structure in your JavaScript file.

Suppose the JSON data is stored in a variable called data. Here is a basic implementation on how to handle this task:

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

Step 2: Using Object.keys() and forEach()

Next, we will use the Object.keys() method to retrieve the keys of the metrics property and iterate over them with the forEach() loop. This way, you can avoid hardcoding the metric names. Here’s how to do it:

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

Explanation

Object.keys(data.metrics): This retrieves an array of metric names dynamically.

forEach(): This method iterates over each metric name.

Creating an object: For each metric, a new object is created which includes the metric's name and the p75 value.

Pushing to results: Finally, the constructed object is added to the results array.

Step 3: Outputting the Result

After running the above code, you’ll obtain an array of objects, formatted neatly:

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

This output is now ready to be used in your HTML fields, allowing for a clean and structured presentation of your metrics without knowing their names in advance.

Conclusion

Accessing child nodes of a JSON structure in JavaScript dynamically is a powerful technique that can greatly enhance your application's flexibility. Using Object.keys() along with forEach() allows you to simplify your data handling and ensures that your code remains clean and efficient.

By following the steps outlined above, you can easily extract unknown child nodes from a JSON object, making your tools more adaptable to varying data structures.

Feel free to implement this strategy in your projects and enhance your JavaScript skills as you go!