Http

CORS 跨網域資訊存取 Cross origin resource sharing

Use Preflight request to negotiate the request can be CORS or not.

the negotiated request use HTTP method called OPINON.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS

使用情境：

在網頁端直接存取其他WebServer 提供的API，對網頁端的好處是無需建置WebServer提供網頁檔案。直接在網頁端指定API HOST

Cache

• nginx

  • Use sendfiles off (無論如何nginx 都會重新讀取檔案)

• CloudFlare

• Add hash in app file such as bundle.js

• Cache-control 指定cache多久才過期，e.g. max-age=3600

• no-store : 無cache

• no-cache: 會發起request 檢查e-tag 或 Last-modfied

no-store, no-cache, private, public, max-age=3600

一次可以指定多個值，並以，分隔。

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control

• 304 Not modified

  • There is a cache file at browser, and send if-modified-since in request header, if doc is not modified, 304 will return.

• 200 OK (from cache)

  • Doesn't execute request to server, use stored file at cache instead.

http://fanli7.net/a/bianchengyuyan/JS-HTML-WEB/20140309/476996.html

http://div.io/topic/854

https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching

Cache-Control 會影響browser 是否要檢查browser cache, 如果尚在時間內則使用browser端的檔案而不發起request

若否，比方說max-age = 0 則進到if-modifed-since 與etag 的確認