代理unpkg的资源

http-proxy-unpkg.js

const app = require('express')();
const path = require('path')
const fs = require('fs')
const { createProxyMiddleware } = require('http-proxy-middleware');
const mcache = require('memory-cache')

const getCacheFilePath = req => path.join('cache', Buffer.from(req.originalUrl || req.url).toString('base64') )

app.use('/unpkg', (req, res, next) => {
  req.cacheFilePath = getCacheFilePath(req)
  const headers = mcache.get(req.cacheFilePath)
  fs.exists(req.cacheFilePath, (exists) => {
    if (exists && headers) {
      for (const key in headers) {
        res.header(key, headers[key])
      }
      fs.createReadStream(req.cacheFilePath).pipe(res)
    } else {
      next()
    }
  })
})

app.use('/unpkg', createProxyMiddleware({
  target: 'https://unpkg.com/',
  changeOrigin: true,
  pathRewrite: {'^/unpkg' : ''},
  onProxyRes: (proxyRes, req, res) => {
    if (proxyRes.headers.location) {
      proxyRes.headers.location = '/unpkg' + proxyRes.headers.location
    } else {
      proxyRes.pipe(fs.createWriteStream(req.cacheFilePath))
      mcache.put(req.cacheFilePath, proxyRes.headers, 24 * 60 * 60 * 1000) // cache header in memory for one day
    }
  }
}));

app.listen(process.env.MDF_PROXY_PORT || 3000)