I. Web App The concept that corresponds to the Web App is the-Native App local application. In the age of movement, users spend 87% of their time Native Apps and only 13% of the time using Web Apps. However, the S a big BUT-87% of the time, 80% contributed to the first three Apps, that is, if your Native App is not the user's high frequency of use of the first three words, then basically developed no one to use. So in this case, it's better to make a web app that lets users use it occasionally from time to time. So there is the concept of PWA. II. Progressive web App The role of PWA is to enhance the user experience and meet one-off requirements), the core of which is to make a Web App deliver the same reliable, stable, secure, and interactive user experience as the Native App. Handwriting a logical tree:) What's interesting here is the caching strategy. Includes, but is not limited to (slightly advanced, maybe programmers can understand): Cache, Falling back to net...