How does WeChat Mini Programs preview in real time?

recently, I have been working on Mini Program, using the Mini Program development tool, which has preview and remote debugging functions, and a corresponding preview interface on the left side of the tool. But now I want to debug the real phone on my phone. My question now is:

how to do this I modified the code in the development tool, saved or pressed the corresponding shortcut keys, and the page corresponding to the real machine (Wechat Mini programs) will also be automatically updated. Now I have tried the preview and remote debugging functions will not automatically refresh the page in Wechat, I now modify a line of js, to scan the code to see the corresponding effect, this is not realistic.
in addition: what"s the difference between scanning QR code preview and automatic preview in the preview function?

Thank you!

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May.10,2021

automatic preview is the real-time preview you say you need. Each change needs to be compiled, and the shortcut key seems to be Shift+Ctrl+P

then Mini Program will be reopened on the phone, but there is a failure, that is, sometimes it will not be refreshed

1. Scan code preview needs to scan code, automatic preview does not need to scan code, developer tools need to be consistent with Wechat account, need to click "compile and preview"
2. Developers' tools need to be recompiled every time the code is modified, and real-time preview is not realistic. Because there is no real-time remote debugging function

as mentioned above, this function is impossible to open, for the sake of security

Mini Program is not web, when you finish writing the code to see in your mobile phone, there are a lot of compilation links, so I don't think this function can be realized.

there is no such feature. Either debug remotely, preview or preview automatically

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