How to Dynamically Populate a Sub-option List Based on JSON Data in jQuery

Learn how to create a cascading dropdown list using jQuery that populates a second dropdown based on selection from a first dropdown, by utilizing JSON data.
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How to Dynamically Populate a Sub-option List Based on JSON Data in jQuery

In modern web development, creating interactive user interfaces is essential for an engaging experience. One common requirement is to dynamically populate a dropdown menu based on the selection from another dropdown. This guide will guide you through the process of achieving this with jQuery and JSON data.

The Problem

Imagine you have a list of districts in a city, and based on the selected district, you want to show the respective wards. This is a common scenario where you’d want the second dropdown (wardId) to get its options dynamically based on the selection from the first dropdown (distId). For example, selecting "dist 1" should populate the wardId dropdown with wards 1, 2, and 3.

In this post, we'll address how to pull the relevant data from a JSON structure and populate the wardId dropdown accordingly.

Understanding the JSON Structure

Before diving into the solution, let’s take a look at the JSON structure we'll be using. The JSON data is structured hierarchically, where a city contains several districts, and each district contains an array of wards.

Here's a simplified version of the JSON we’ll be working with:

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

Key Points of the JSON:

Each city contains multiple districts.

Each district is an array of wards, which contain their names.

The Solution

To implement this cascading dropdown functionality using jQuery, follow these steps:

Step 1: Setup Your HTML

You'll need two select elements in your HTML:

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

Step 2: Implement the jQuery Logic

In your JavaScript, you will listen for changes on the distId dropdown. Based on the selected district, you will fetch the corresponding wards from the JSON and populate the wardId dropdown.

Here’s how you can do it:

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

Explanation of the Code

The event listener ($("# distId").on("change", function() {...})) triggers whenever the district dropdown selection changes.

The JSON object is iterated through to find the corresponding wards for the selected district.

Any existing options in the wardId select are cleared using $("# wardId").empty().

New options are populated based on the selected district, utilizing the forEach method to append option elements.

Conclusion

By following the steps outlined above, you can easily create a dynamic cascading dropdown list using jQuery that pulls data from a JSON structure. This approach not only enhances user experience but also ensures that your web applications are interactive and user-friendly.
With just a few lines of code, you can implement this functionality efficiently while keeping your code organized.

Feel free to ask any questions or share your experiences with similar implementations in the comments below!