It was originally intended to be compatible with browsers such as Netscape and FireFox, but these browsers do not support style.pixelLeft, so you have to use style.left and the like (style.pixelLeft has no units for numbers, and style.left has units for text). In fact, During use, I found that the effect was very poor and there was a delay, so I still used style.pixelLeft. The disadvantage is that it only supports IE series browsers.