Javascript implements simple modal window and grayed out background javascript skills

At noon yesterday, a modal window was required for the project. I remembered that the project manager of the previous company had done a very good modal window. So far, I have no idea about the implementation principle, and I have no time to analyze it, I tried to do one by myself. It took a day to finally complete the process. I would like to share it with you. I also hope you can give more comments. I am very happy to have posted an article on the blog for the first time. Nothing can be said. js is used to block pages with an iframe. On the iframe, a p layer is built on the js object-oriented interface. Some of them are js-based dynamic style generation.
ModeWindow. js

The Code is as follows:

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