first of all, here is a rookie developed by WeChat Mini Programs. I don"t know what"s going on. I can"t preview whether I write it myself or download someone else"s source code. Duniang said that as long as I saved it, but it didn"t work even if I pressed ctrl+s many times. The 
that has always been displayed is the page of this Wechat developer tool, and the preview is always grayed out, even if I download someone else"s source code. I typed it according to a word in the teaching video, but it was still the same page. After watching the teacher in the video, there was a change, but this is still the case. I didn"t see a similar problem or solution on the Internet. I beg you, gods, to help me solve my doubts. Thank you very much. Because it is completely self-taught, I have only used php and dw to do web pages before. I think that if php wants to see the effect, there are a lot of settings. I wonder if this should also be set up, and whether it must be appid before you can see it!