Скачать или смотреть How to Sync Dropdown Options Dynamically in JavaScript

Learn how to dynamically link two dropdowns in JavaScript and handle unique cases like options not being available in one of them.
---
This video is based on the question https://stackoverflow.com/q/76248836/ asked by the user 'cvz' ( https://stackoverflow.com/u/15759193/ ) and on the answer https://stackoverflow.com/a/76249106/ provided by the user 'OldPadawan' ( https://stackoverflow.com/u/3801953/ ) 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 to select a particular dropdown when an option is selected in other dropdown?

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.
---
Synchronizing Dropdown Selections in JavaScript

When creating dynamic forms, a common requirement arises where two dropdowns (select elements) may need to synchronize their selected values based on specific criteria. For instance, you might have a scenario where two dropdowns contain similar options, but one of them has a value that the other does not. In this blog, we will explore how to seamlessly synchronize shadow selections across two dropdowns using jQuery.

The Problem: Linking Two Dropdowns

Imagine you have two dropdowns for car brands – the first dropdown includes Audi, while the second dropdown does not. If a user selects Audi in the first dropdown, we want to automatically refer to a default option in the second dropdown. However, if a valid match is found in the second dropdown, that option should be selected instead.

Technical Challenge

Dropdown 1 (cars1): Includes options like Volvo, Saab, Mercedes, Audi.

Dropdown 2 (cars2): Includes Volvo, Saab, Mercedes, but not Audi.

When Audi is selected in cars1, we need to select a default option in cars2 while ensuring that valid selections still sync properly.

The Solution: jQuery Implementation

To create this synchronized behavior between the dropdowns, we will utilize jQuery. Below are the steps involved in resolving the problem.

Step 1: Set Up HTML Structure

Firstly, let’s set up the HTML for the dropdowns. Here’s how you can structure it:

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

Step 2: Write the JavaScript Code

After setting up our HTML, we will implement the JavaScript functionality using jQuery. The following code snippet will create the desired relationship between the two dropdowns:

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

How the Code Works

When a dropdown's selection changes:

The ID of the changed dropdown is grabbed.

The value of the selected option is checked against the options available in the targeted dropdown (linked via data-target).

If a match is found in the target dropdown, it is selected. If no match exists (for example, Audi), it defaults to the "Please-Select" option.

Conclusion

Synchronizing options between dropdowns allows for a smoother user experience, particularly when dealing with dependent selections. This implementation in jQuery effectively addresses the specific needs of dropdown menus by maintaining clarity and functionality regardless of the options available. Feel free to extend the code based on your requirements, and enjoy the flexibility that dynamic forms can bring to your applications!