The key to optimizing web page performance: in-depth analysis of the selection of reflow and redraw technologies

The key to improving web page performance: Analysis of technology selection for reflow and redrawing

With the popularization and development of the Internet, web page performance has become an important indicator that users pay attention to one. A good web page should load quickly and interact smoothly. To achieve such a goal, the selection of reflow and redrawing technologies is particularly important.

Reflow and redraw are two key operations performed by the browser when rendering a web page. Reflow refers to calculating the geometric properties of elements in the document layout, such as position, size, etc. Redrawing, on the other hand, applies the element's style to the content and draws it. Frequent execution of these two operations will consume a large amount of computing resources, resulting in reduced web page performance.

In order to improve web page performance, we can reduce its impact on web page rendering by selecting appropriate reflow and redraw technology. The following is an analysis of several common technology selections:

1. Use CSS transform to replace the top/left attribute

In web development, we often use the top/left attribute to Control the position of elements, but such operations will cause reflow. In comparison, the CSS transform attribute can change the position of elements through GPU acceleration, thereby avoiding reflow operations and improving performance.

2. Use the will-change attribute

The will-change attribute is used to prompt the browser that an element is about to change, thereby optimizing the browser's rendering process. By setting the element's transform or opacity attribute to will-change, you can avoid frequent reflow and redraw operations and improve web page performance.

3. Separate read and write operations

In web development, we often need to add, delete, modify and check the DOM. In order to reduce the cost of reflow and redrawing, read and write operations can be separated as much as possible. For example, combine multiple DOM operations into one execution, or cache elements that need to be modified frequently and update them all at once.

4. Avoid frequent style modifications

Frequently modifying the style of elements will also lead to frequent reflow and redraw operations. In order to reduce unnecessary performance losses, try to avoid frequently modified style attributes. Styles can be centrally managed through CSS classes and applied to elements at once.

5. Use animation performance optimization tips

When animation effects are used in a web page, the frequency of reflow and redraw will be higher. In order to improve the performance of animations, you can use some optimization techniques. For example, use CSS translate instead of top/left properties to implement displacement animation; for complex animations, you can use requestAnimationFrame() to achieve smooth animation effects.

6. Delayed execution and throttling

For some operations that need to be performed frequently, you can reduce the impact on performance by delaying execution and throttling. For example, in a page scroll event, you can set a timer to delay the reflow and redraw operations, or use a throttling function to control the frequency of reflow and redraw.

7. Use virtual DOM technology

Virtual DOM technology can help us optimize the performance of DOM operations. By manipulating the virtual DOM in memory instead of directly manipulating the real DOM, the number of reflow and redraw operations can be reduced. When all modifications are completed, apply the changes to the virtual DOM to the real DOM at once.

When choosing reflow and redrawing technologies, you need to comprehensively consider the specific needs and performance requirements of the web page. Different technology selections may bring different performance advantages and development costs, which require trade-offs in actual projects. At the same time, you also need to pay attention to the reasonable use of technology to avoid excessive optimization that reduces the readability and maintainability of the code.

In general, the selection of reflow and redraw technology is crucial to improving web page performance. Through reasonable selection and use of relevant technologies, the impact on web page rendering can be reduced and user experience improved.

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