Which one consumes more performance, reflow or redraw?

Reflow consumes more performance. Reflow is a very performance-consuming operation because it requires traversing the entire document tree and recalculating the position of each element, while redrawing only requires updating the style attributes of the element. In contrast, Said to be more efficient. In order to reduce the performance consumption of reflow and redraw, some optimization measures can be taken. By avoiding frequent changes to the style attributes of elements, using batch operations and virtual DOM technology, the number of reflow and redraw can be reduced and the performance of the page can be improved.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

In computer graphics, reflow and repaint are two important concepts. They all involve performance consumption during web page layout and rendering.

Reflow means that when the layout of the web page changes, the browser needs to recalculate the position and size of the elements and then re-layout the entire page. This process is relatively slow because it requires traversing the entire document tree and recalculating the position of each element. Reflow is a very performance-intensive operation, especially when there are a large number of elements in the page that need to be rearranged.

Redrawing means that when the style of the web page changes, the browser needs to redraw the appearance of the element. This process is relatively fast because it only requires updating the element's style properties and not recalculating the element's position. The performance cost of redrawing is relatively low, especially in modern browsers, which use various optimization techniques to speed up the redrawing process.

The performance consumption of reflow and redraw is different, but there is a certain correlation between them. When an element's style attributes change, the browser will first reflow and then redraw. This is because reflow is a prerequisite for redrawing, and only when the element's position and size are determined can the browser correctly draw the appearance of the element.

So, which one consumes more performance, reflow or redraw? The answer is reflow. Reflow is a very performance-intensive operation because it requires traversing the entire document tree and recalculating the position of each element. Redrawing only needs to update the style attributes of the element, which is relatively more efficient.

In order to reduce the performance consumption of reflow and redraw, we can take some optimization measures. First, try to avoid frequently changing the style properties of elements, especially those that trigger reflow, such as width, height, position, etc. You can instead change the position and size of an element by using the CSS3 transform property, since transform does not trigger reflow.

Secondly, you can use batch operations to change the style attributes of elements. Combining multiple style changes into one operation can reduce the number of reflows and redraws and improve performance.

In addition, virtual DOM technology can be used to optimize the page rendering process. Virtual DOM is a technology that abstracts the state of the page into a JavaScript object and performs minimal DOM operations by comparing the difference between the two states before and after. Virtual DOM can reduce the number of reflows and redraws and improve performance.

In short, reflow and redraw will have an impact on the performance of the page, but reflow is a more performance-consuming operation. By avoiding frequent changes to the style attributes of elements and using batch operations and virtual DOM technology, the number of reflows and redraws can be reduced and the performance of the page can be improved.

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