Static cache middleware for koa.

Differences between this library and other libraries such as static:

• There is no directory or index.html support.
• You may optionally store the data in memory - it streams by default.
• Caches the assets on initialization - you need to restart the process to update the assets.(can turn off with options.preload = false)
• Uses MD5 hash sum as an ETag.
• Uses .gz files if present on disk, like nginx gzip_static module

Forked from https://github.com/koajs/static-cache, refactor with TypeScript to support CommonJS and ESM both.

npm install @eggjs/koa-static-cache

const path = require('path');
const { staticCache } = require('@eggjs/koa-static-cache');

app.use(staticCache(path.join(__dirname, 'public'), {
  maxAge: 365 * 24 * 60 * 60
}));

• options.dir (str) - the directory you wish to serve, default to process.cwd.
• options.maxAge (int) - cache control max age for the files, 0 by default.
• options.cacheControl (str) - optional cache control header. Overrides options.maxAge.
• options.buffer (bool) - store the files in memory instead of streaming from the filesystem on each request.
• options.gzip (bool) - when request's accept-encoding include gzip, files will compressed by gzip.
• options.usePrecompiledGzip (bool) - try use gzip files, loaded from disk, like nginx gzip_static
• options.alias (obj) - object map of aliases. See below.
• options.prefix (str) - the url prefix you wish to add, default to ''.
• options.dynamic (bool) - dynamic load file which not cached on initialization.
• options.filter (function | array) - filter files at init dir, for example - skip non build (source) files. If array set - allow only listed files
• options.preload (bool) - caches the assets on initialization or not, default to true. always work together with options.dynamic.
• options.files (obj) - optional files object. See below.

For example, if you have this alias object:

const options = {
  alias: {
    '/favicon.png': '/favicon-32.png'
  }
}

Then requests to /favicon.png will actually return /favicon-32.png without redirects or anything. This is particularly important when serving favicons as you don't want to store duplicate images.

You can pass in an optional files object. This allows you to do two things:

Instead of doing:

app.use(staticCache('/public/js'))
app.use(staticCache('/public/css'))

You can do this:

const files = {};

// Mount the middleware
app.use(staticCache('/public/js', {}, files));

// Add additional files
staticCache('/public/css', {}, files);

The benefit is that you'll have one less function added to the stack as well as doing one hash lookup instead of two.

For example, if you want to change the max age of /package.json, you can do the following:

const files = {};

app.use(staticCache('/public', {
  maxAge: 60 * 60 * 24 * 365
}, files));

files['/package.json'].maxAge = 60 * 60 * 24 * 30;

You can pass in a lru cache instance which has tow methods: get(key) and set(key, value).

const LRU = require('lru-cache');
const files = new LRU({ max: 1000 });

app.use(staticCache({
  dir: '/public',
  dynamic: true,
  files,
}));

MIT

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