Troubleshooting records of garbled characters

Recently, I encountered the problem of modifying an old project. The entire project uses gb2312 encoding. Now I want to add a component application, which must be UTF-8 encoded. After I made a special UTF-8 processing for this page in Web. config, the problem arises: The post data of another function is garbled. After thinking about it, the page will be encoded with JS escape before submission, and then submitted. The server side will handle it with server. urldecode, and the problem will be barely solved. But I always think this kind of processing is very awkward .....