Toggle Dropdown Event Listeners with a Button in JavaScript

Learn how to efficiently toggle event listeners for dropdown lists using a button in JavaScript while adhering to DRY principles.
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This video is based on the question https://stackoverflow.com/q/68824746/ asked by the user 'user16405900' ( https://stackoverflow.com/u/16405900/ ) and on the answer https://stackoverflow.com/a/68824884/ provided by the user 'Barmar' ( https://stackoverflow.com/u/1491895/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Toggle Dropdown Event Listeners with a Button in JavaScript

Good evening, fellow coders! Have you ever found yourself in a situation where you need to manage multiple dropdowns but want to streamline the process using a single event listener? Today's topic hits on that very concept: toggling between dropdown lists using a button to control which dropdown has an active event listener.

In this post, we'll break down how to efficiently manage event listeners in JavaScript, ensuring you stick to the best coding practices like DRY (Don't Repeat Yourself). Let's dive in!

The Problem at Hand

You want to utilize a button that toggles event listeners between two dropdown lists. Initially, one dropdown should be monitored for changes, but upon clicking the button, the other dropdown should take over that responsibility.

Here's the simplified HTML structure we have:

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

With this setup, we initially assign an event listener to the first dropdown (my-select) that logs changes to the console. However, we want to remove the listener from this dropdown and add it to the second dropdown (my-select-one) when the button is clicked.

Proposed Solution

Let's walk through a solution that effectively toggles the event listeners between the dropdowns.

Define a variable to hold the current dropdown:
We start by defining a variable ites, which holds the ID of the current dropdown we're monitoring.

Create a button function:
This function, when triggered, will do the following:

Remove the event listener from the current dropdown.

Toggle the ites variable to point to the other dropdown.

Add the event listener to the newly selected dropdown.

Create the dropdown event function:
This function will execute whenever there's a change in the dropdown value and will log that change to the console.

Here's the complete JavaScript code:

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

How It Works

When the button is clicked: The buttonFunction() gets called, which first removes the event listener from the dropdown currently tracked by ites. It then toggles ites to point to the other dropdown and reassigns the event listener.

Logging Changes: The dropdownFunction() logs the current dropdown ID and the selected value to the console efficiently each time there's a change.

Final Thoughts

This approach ensures that you avoid repeating code while effectively managing your event listeners. You can extend this methodology for additional dropdowns as needed without complicating your code.

Remember, proper management of event listeners not only makes your code cleaner but improves its maintainability and scalability. Enjoy coding, and happy toggling!

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