Function assetPreprocessing

middleware/asset-preprocessing.js:13–26

(req, res, next)

const regex = /\/cb-\d+\//

export default function assetPreprocessing(req, res, next) {
  if (req.path.startsWith('/assets/')) {
    // We're only confident enough to set the *manual* surrogate key if the
    // asset contains the cache-busting piece.
    if (regex.test(req.url)) {
      // We remove it so that when `express.static()` runs, it can
      // find the file on disk by its original name.
      req.url = req.url.replace(regex, '/')
      // The Cache-Control is managed by the configuration
      // for express.static() later in the middleware.
    }
  }
  return next()
}