packages/@vue/cli-service/lib/util/prepareProxy.js
function mayProxy (pathname) {
    const maybePublicPath = path.resolve(appPublicFolder, pathname.slice(1))
    return !fs.existsSync(maybePublicPath)
  }
function mayProxy (pathname) {
    const maybePublicPath = path.resolve(appPublicFolder, pathname.slice(1))
    return !fs.existsSync(maybePublicPath)
  }
function mayProxy ( pathname ) { const maybePublicPath = path . resolve ( appPublicFolder , pathname . slice ( 1 ) ) return ! fs . existsSync ( maybePublicPath ) }
Otherwise, if proxy is specified, we will let it handle any request except for files in the public folder.
Otherwise if proxy is specified we will let it handle any request except for files in the public folder .