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This article will explain in detail why you should not use CSS Expression as far as possible. The content of the article is of high quality, so the editor will share it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Use JavaScript expressions in CSS Expression. The CSS property is set based on the result of the evaluation of the JavaScript expression. CSS Expression does not work in other browsers, so it is useful to set it separately for IE in cross-browser coding. CSS Expression is supported from IE5. Let's take a look at the following code: background-color: _ expression ((new Date () ()). GetHours ()% 2? "# F00": "# 00F"); the above code uses CSS Expression to switch the background color every hour.

The problem with CSS Expression is that it calculates a lot more frequently than you think. It will be recalculated not only when the page is displayed and zoomed, but also when the page scrolls or even moves the mouse. Add a counter to CSS Expression to track how often expressions are evaluated. You can easily reach more than 10000 calculations by moving the mouse on the page. One way to reduce the number of CSS Expression calculations is to use an one-time expression that assigns the result to the specified style property on the first run and replaces the CSS Expression with this property. If style properties must change dynamically during the page cycle, it is possible to use event handlers instead of CSS expressions. If you have to use CSS Expression, keep in mind that they have to be calculated thousands of times and may have an impact on the performance of your page. Don't let your users feel like opening your page, the machine will become very slow.

On the reasons for trying not to use CSS Expression is shared here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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