Optimizing Cumulative Layout Shift: Should You Use toggle() or classList.toggle()?

Discover the best approach for hiding elements in JavaScript to minimize cumulative layout shift (CLS) and enhance your web performance.
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This video is based on the question https://stackoverflow.com/q/68451787/ asked by the user 'Marcin Rutkowski' ( https://stackoverflow.com/u/15043171/ ) and on the answer https://stackoverflow.com/a/68451996/ provided by the user 'Amal nandan' ( https://stackoverflow.com/u/10706395/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Optimizing Cumulative Layout Shift: Should You Use toggle() or classList.toggle()?

Cumulative Layout Shift (CLS) is a vital metric that measures the visual stability of your web pages. A high CLS score can lead to a frustrating user experience, often caused by elements shifting unexpectedly due to changes in the DOM. If you're dealing with layout shifts due to hiding elements with JavaScript, you may wonder whether to use .toggle() or .classList.toggle("displayNoneClass"). Let's dive deeper into this issue to identify the best approach for optimizing CLS.

Understanding the Problem

When you hide elements on your page, it can sometimes trigger layout shifts that affect your website’s performance and user experience. You might be using JavaScript to toggle the visibility of certain elements, but the technique you choose can have different effects on your element's display properties and overall CLS.

The Two Methods

Using .toggle(): This method is commonly found in jQuery and modifies the visibility of an element by changing the style directly in the jQuery cache.

Using .classList.toggle("displayNoneClass"): This approach adds or removes a CSS class that controls the display property of the element, potentially avoiding direct manipulation of the element’s style.

Analyzing the Techniques

The best method to use depends on the current display property of the element you're attempting to hide. Here’s how each option stacks up:

1. Using .toggle()

Pros:

Quick and straightforward to implement.

Changes are made directly in memory, typically preventing the need for additional style restoration.

Cons:

It does not manage CSS class rules, which may lead to inconsistencies if the element's styling changes over time.

2. Using .classList.toggle("displayNoneClass")

Pros:

More control over CSS styles, allowing you to restore the previous display property immediately by toggling a specific class.

Reduces the likelihood of unexpected layout shifts since you're not directly manipulating the inline style.

Cons:

Requires you to define and handle a CSS class separately, which could add complexity if you have many elements to manage.

Which is Better for CLS Optimization?

In general, your choice should be based on the desired outcome and the current display status of the element:

If the element is display: inline and you want to hide it using display: none;, you must ensure to restore its original state. In this case, using .classList.toggle("displayNoneClass") can be more effective.

If you prefer a straightforward approach without worrying about CSS priority, .toggle() may work just fine, provided you are aware that it modifies only jQuery cache.

Conclusion

Both methods have their merits, and your choice will largely depend on your specific requirements and existing styles. If you prioritize minimizing CLS and maintaining visual consistency in your layout, leveraging class toggling is often the safer bet. However, if you have a clear understanding of the elements' states and prefer simpler code, .toggle() may suffice.

When developing web components, always place performance and user experience at the forefront of your decisions. By adopting appropriate techniques to manage element visibility, you can significantly enhance the stability of your web applications.