Reflow, redraw and reflow: Which optimization method is most effective in improving web page performance?

Reflow, redraw and reflow: Which one improves web page performance?

In web development, we often hear terms related to performance - reflow, redraw and reflow. These terms describe different stages in the web page rendering process and are critical to understanding and optimizing web page performance. In this article, we'll explore the concepts of reflow, repaint, and reflow, and provide some code examples that can improve the performance of your web pages.

First, let us understand the meaning of reflow, redraw and reflow.

Reflow refers to the process in which the browser needs to recalculate the position and size of elements due to factors such as changes in the DOM structure or changes in window size during the web page rendering process. Reflow is a very performance-intensive operation because it causes other parts of the web page to be rearranged and redrawn.

Repaint refers to the process in which the appearance of an element changes during the rendering process of a web page, but does not affect its position and size. Redrawing consumes less performance than reflowing.

Reflow (layout) is a comprehensive name for rearrangement and redrawing. It refers to the process in which the browser relays out and renders the web page based on the latest DOM structure and style information.

So, how to improve the performance of web pages? Here are some optimization strategies and code examples to consider:

1. Reduce the number of reflows:

   • Merge multiple DOM operations: by using DocumentFragment or once Modify multiple DOM attributes to reduce multiple rearrangements.
   • Use class instead of style attribute: avoid directly modifying the style attribute of an element, but change the style by adding or removing CSS classes.

2. Reduce the number of redraws:

   • Use CSS animations instead of JavaScript animations: CSS animations are accelerated by the browser's hardware and can reduce the number of redraws. .
   • Use transform and opacity attributes: These two attributes can change the appearance of elements without causing reflow and redrawing.

3. Use requestAnimationFrame:

   • requestAnimationFrame is an API provided by the browser that can optimize the performance of animation effects. It calls the callback function before each frame to ensure that the animation is rendered at the best time in the browser, thereby reducing unnecessary reflows and redraws.

These optimization strategies and code examples can help us reduce the number of reflows, redraws and reflows, thereby improving the performance of web pages. However, it should be noted that while optimizing web page performance, we must also maintain code readability and maintainability.

To sum up, reflow, redraw and reflow are important links in the web page rendering process and have an important impact on web page performance. Through reasonable optimization strategies and coding practices, we can reduce the number of these operations and improve the performance of web pages. The most important thing is that in the process of optimizing web page performance, we also need to keep the code readable and maintainable.

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