How to avoid redraw and reflow

Methods to avoid redrawing and reflow include "use classes to modify styles in batches", "use CSS3 animation or transform to achieve animation effects", "avoid frequently reading layout information", "use document fragments for DOM 7 types: "Operation", "Use position: absolute or fixed for animation", "Cache calculation results" and "Batch modify styles": 1. Modify the class attribute of the element, you can modify multiple styles at one time, etc.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Redrawing and reflowing are necessary operations when the browser renders the page, but excessive redrawing and reflowing will cause performance problems. The following are some common methods to avoid redrawing and reflowing:

1. Use class to modify styles in batches: By modifying the class attribute of an element, you can modify multiple styles at once to avoid frequent changes. A single style modification results in redraws and reflows.

2. Use CSS3 animation or transform to achieve animation effects: Use CSS3 animation properties or transform properties to achieve animation effects. These properties are usually processed at the GPU level without causing reflow. Performance is better.

3. Avoid frequently reading layout information: In JavaScript, if layout information (such as offsetTop, offsetLeft, etc.) is frequently read, the browser will be forced to reflow. Try to avoid such operations, or cache them to reduce the number of reflows.

4. Use document fragments (DocumentFragment) for DOM operations: By first creating a document fragment, performing DOM operations on it, and finally adding the document fragment to the document at once, you can reduce Frequent reflux.

5. Use position:absolute or fixed for animation: Use position:absolute or fixed relative to other elements for positioning, so that it will not affect the layout of other elements.

6. Cache calculation results: If you need to read a calculation result multiple times, you can cache the results to avoid repeated calculations and reduce the number of reflows.

7. Batch modification of styles: If you need to modify the style of an element multiple times, it is best to apply all the styles at once by changing its class attribute, rather than directly modifying the element multiple times. style attribute.

In general, methods such as avoiding frequent modification of styles, using appropriate CSS properties to achieve animation effects, reducing frequent reading of layout information, and reasonably optimizing DOM operations can all help. Reduce redraws and reflows, improving page performance and user experience.

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