JQuery-webpage skin replacement implementation code _ jquery

Using jQuery for web page skin replacement is indeed a very clever and good choice. This is my learning of jQuery. It is very useful and I wrote it down, I hope you will have better methods or insufficient code. I am also a beginner. I hope you will encourage each other to learn from each other. The following code is used:
First, the HTML page code is as follows:

The Code is as follows:

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