How to Toggle Multiple DIVs in JavaScript with classList.toggle

---

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---

In web development, you often need to manipulate HTML elements dynamically. One common task is toggling classes on multiple elements. In this post, we’ll walk through how to effectively toggle the classes of several <div> elements using JavaScript. This is particularly useful when you want to change a style or functionality for a group of elements at once.

The Problem: Changing Multiple DIVs

Suppose you have several <div> elements in your HTML, all sharing a common class called oldwidth. You want to toggle these elements to a new class called newwidth when a specific action occurs, such as a button click. Here’s an example of the existing HTML:

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

The goal is to change all these oldwidth classes to newwidth. However, many developers encounter a stumbling block — their existing code only toggles the first element it finds, leaving the rest unchanged.

The Initial Attempt

Here's what you might have tried initially, which would only affect the first matching element:

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

This code correctly selects the first element but fails to iterate through all elements with the class oldwidth. Thus, only one div gets modified, while the rest remain unchanged.

The Solution: Looping Through All Elements

To achieve the desired effect of toggling all div elements, you'll need to iterate over all elements with the oldwidth class. Here’s how you can do it:

Select All Elements: Use getElementsByClassName to grab all elements with the oldwidth class.

Loop Through Each Element: Use a for loop to access each individual element.

Here's the complete code:

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

How It Works

Iteration: The for loop iterates over this collection. The variable i starts at 0 and increments until it reaches the length of the elements collection.

Conclusion

By using a loop with getElementsByClassName, you can efficiently toggle classes on multiple elements in JavaScript. This approach not only resolves the issue of only modifying the first element but also ensures a more interactive and dynamic user experience on web pages.

Now that you've got the hang of toggling classes on multiple div elements, you can apply this technique to various situations in your web projects. Happy coding!