When a user accesses a website, the browser caches web resources after the first load to reduce the server pressure and speed up the second load.

Refer to the article

1. Practice this one and thoroughly understand the browser caching mechanism

2. HTTP cache – MDN

3. If the ETag value in the HTTP response header changes, does that mean that the file content must have changed #113

Noun explanation

  • memory cache: cache to memory, browser closed after the next need to reload
  • disk cache: Cache to disk, browser closed and then open cache is also effective
  • Cache-Control: max-age=30Cache expiration timeno-cache/max-age=<seconds> Detailed introduction
  • Date: Mon, 26 Apr 2021 16:49:50 GMTThe time point at which the current resource server responds is converted to China time zone plus 8 hours
  • ETag: "6084338b-c7"The ETag of the current file will be modified after the file is modified, but the file will not be modifiedLast-ModifiedModification can also lead toETagChange, see reference article 3
  • Last-Modified: Sat, 24 Apr 2021 15:04:43 GMTTime when the file was last modified
  • Server: nginx / 1.18.0Server Type

Nginx simple configuration

server { listen 8089; location / { add_header Cache-Control max-age=100,immutable; root D:/soft/qq/Desktop/0820/HTML/nginx; }}Copy the code

Cache judgment logic flow chart