對 Express 除錯

如果要查看 Express 中使用的所有內部日誌，在您啟動應用程式時，請將 DEBUG 環境變數設為 express:*。

$ DEBUG=express:* node index.js

在 Windows 中，使用對應指令。

> $env:DEBUG = "express:*"; node index.js

對 express generator 產生的預設應用程式執行這個指令，會列印下列輸出：

$ DEBUG=express:* node ./bin/www
  express:router:route new / +0ms
  express:router:layer new / +1ms
  express:router:route get / +1ms
  express:router:layer new / +0ms
  express:router:route new / +1ms
  express:router:layer new / +0ms
  express:router:route get / +0ms
  express:router:layer new / +0ms
  express:application compile etag weak +1ms
  express:application compile query parser extended +0ms
  express:application compile trust proxy false +0ms
  express:application booting in development mode +1ms
  express:router use / query +0ms
  express:router:layer new / +0ms
  express:router use / expressInit +0ms
  express:router:layer new / +0ms
  express:router use / favicon +1ms
  express:router:layer new / +0ms
  express:router use / logger +0ms
  express:router:layer new / +0ms
  express:router use / jsonParser +0ms
  express:router:layer new / +1ms
  express:router use / urlencodedParser +0ms
  express:router:layer new / +0ms
  express:router use / cookieParser +0ms
  express:router:layer new / +0ms
  express:router use / stylus +90ms
  express:router:layer new / +0ms
  express:router use / serveStatic +0ms
  express:router:layer new / +0ms
  express:router use / router +0ms
  express:router:layer new / +1ms
  express:router use /users router +0ms
  express:router:layer new /users +0ms
  express:router use / &amp;lt;anonymous&amp;gt; +0ms
  express:router:layer new / +0ms
  express:router use / &amp;lt;anonymous&amp;gt; +0ms
  express:router:layer new / +0ms
  express:router use / &amp;lt;anonymous&amp;gt; +0ms
  express:router:layer new / +0ms

當對應用程式發出要求時，您會看到 Express 程式碼中指定的日誌：

  express:router dispatching GET / +4h
  express:router query  : / +2ms
  express:router expressInit  : / +0ms
  express:router favicon  : / +0ms
  express:router logger  : / +1ms
  express:router jsonParser  : / +0ms
  express:router urlencodedParser  : / +1ms
  express:router cookieParser  : / +0ms
  express:router stylus  : / +0ms
  express:router serveStatic  : / +2ms
  express:router router  : / +2ms
  express:router dispatching GET / +1ms
  express:view lookup "index.pug" +338ms
  express:view stat "/projects/example/views/index.pug" +0ms
  express:view render "/projects/example/views/index.pug" +1ms

如果只想查看來自路由器實作的日誌，請將 DEBUG 的值設為 express:router。同樣地，如果只想查看來自應用程式實作的日誌，請將 DEBUG 的值設為 express:application，以此類推。 Likewise, to see logs only from the application implementation, set the value of DEBUG to express:application, and so on.

`express` 產生的應用程式

express 指令產生的應用程式也會使用 debug 模組，且其除錯名稱空間的範圍限於應用程式的名稱。

舉例來說，如果您使用 $ express sample-app 來產生應用程式，您可以利用下列指令來啟用除錯陳述式：

$ DEBUG=sample-app:* node ./bin/www

您可以指派以逗點區隔的名稱清單，來指定多個除錯名稱空間：

$ DEBUG=http,mail,express:* node index.js

Advanced options

When running through Node.js, you can set a few environment variables that will change the behavior of the debug logging:

Name	Purpose
`DEBUG`	Enables/disables specific debugging namespaces.
`DEBUG_COLORS`	Whether or not to use colors in the debug output.
`DEBUG_DEPTH`	Object inspection depth.
`DEBUG_FD`	File descriptor to write debug output to.
`DEBUG_SHOW_HIDDEN`	Shows hidden properties on inspected objects.

Note

The environment variables beginning with DEBUG_ end up being converted into an Options object that gets used with %o/%O formatters. See the Node.js documentation for util.inspect() for the complete list.

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對 Express 除錯

express 產生的應用程式

Advanced options

`express` 產生的應用程式