在 Express 中提供靜態檔案

To serve static files such as images, CSS files, and JavaScript files, use the express.static built-in middleware function in Express.

The function signature is:

express.static(root, [options])

The root argument specifies the root directory from which to serve static assets. For more information on the options argument, see express.static.

For example, use the following code to serve images, CSS files, and JavaScript files in a directory named public:

app.use(express.static('public'))

現在，您可以載入位於 public 目錄中的檔案：

http://localhost:3000/images/kitten.jpg
http://localhost:3000/css/style.css
http://localhost:3000/js/app.js
http://localhost:3000/images/bg.png
http://localhost:3000/hello.html

To use multiple static assets directories, call the express.static middleware function multiple times:

app.use(express.static('public'))
app.use(express.static('files'))

Express looks up the files in the order in which you set the static directories with the express.static middleware function.

To create a virtual path prefix (where the path does not actually exist in the file system) for files that are served by the express.static function, specify a mount path for the static directory, as shown below:

app.use('/static', express.static('public'))

現在，您可以透過 /static 路徑字首，來載入 public 目錄中的檔案。

http://localhost:3000/static/images/kitten.jpg
http://localhost:3000/static/css/style.css
http://localhost:3000/static/js/app.js
http://localhost:3000/static/images/bg.png
http://localhost:3000/static/hello.html

不過，您提供給 express.static 函數的路徑，是相對於您從中啟動 node 程序的目錄。如果您是從另一個目錄執行 Express 應用程式，保險作法是使用您想提供之目錄的絕對路徑： If you run the express app from another directory, it’s safer to use the absolute path of the directory that you want to serve:

const path = require('path')
app.use('/static', express.static(path.join(__dirname, 'public')))

For more details about the serve-static function and its options, see serve-static.

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