What is DOM Reflow and How Does It Impact Webpage Performance?

DOM Reflow: A Comprehensive Explanation

In the realm of front-end development, "DOM reflow" is a term often encountered when exploring performance optimization. This article aims to clarify its significance and provide insights into how it operates.

A DOM reflow is essentially a process that recalculates the layout of a webpage. This involves computing dimensions, positioning elements, and adjusting the layout of the entire page. It can be triggered by numerous actions, including but not limited to:

• Adding, removing, or modifying elements in the DOM
• Altering content within an element
• Moving elements within the DOM structure
• Applying CSS style changes
• Measuring element properties
• Modifying className attributes
• Resizing the browser window
• Scrolling the page

The impact of DOM reflow can be significant in terms of performance. Each reflow operation involves complex calculations, which can strain the browser's rendering engine. This can result in delays and choppiness in the user interface.

Unlike "visibility: hidden," which simply hides an element without altering the layout, "display: none" causes a DOM reflow because it removes the element from the visual flow and triggers adjustments to the surrounding elements.

Understanding the nature of DOM reflow is crucial for optimizing webpage performance. By minimizing reflows through efficient coding practices, developers can ensure smooth and responsive user experiences.

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