unpkg/server/middleware/findFile.js

107 lines
3.3 KiB
JavaScript

const fs = require('fs')
const path = require('path')
const ResolveExtensions = [ '', '.js', '.json' ]
/**
* Resolves a path like "lib/file" into "lib/file.js" or "lib/file.json"
* depending on which one is available, similar to require('lib/file').
*/
function resolveFile(base, useIndex, callback) {
ResolveExtensions.reduceRight(function (next, ext) {
const file = base + ext
return function () {
fs.stat(file, function (error, stats) {
if (error) {
if (error.code === 'ENOENT' || error.code === 'ENOTDIR') {
next()
} else {
callback(error)
}
} else if (useIndex && stats.isDirectory()) {
resolveFile(path.join(file, 'index'), false, function (error, indexFile, indexStats) {
if (error) {
callback(error)
} else if (indexFile) {
callback(null, indexFile, indexStats)
} else {
next()
}
})
} else {
callback(null, file, stats)
}
})
}
}, callback)()
}
/**
* Determine which file we're going to serve and get its stats.
* Redirect if the request targets a directory with no trailing slash.
*/
function findFile(req, res, next) {
if (req.filename) {
const base = path.join(req.packageDir, req.filename)
// Based on the URL, figure out which file they want.
resolveFile(base, false, function (error, file, stats) {
if (error)
console.error(error)
if (file == null) {
res.status(404).send(`Cannot find file "${req.filename}" in package ${req.packageSpec}`)
} else if (stats.isDirectory() && req.pathname[req.pathname.length - 1] !== '/') {
// Append / to directory URLs.
res.redirect(`${req.pathname}/${req.search}`)
} else {
req.file = file.replace(req.packageDir, '')
req.stats = stats
next()
}
})
} else {
// No filename in the URL. Try to figure out which file they want by
// checking package.json's "unpkg", "browser", and "main" fields.
let mainFilename
const packageConfig = req.packageConfig
const queryMain = req.query.main
if (queryMain) {
if (!(queryMain in packageConfig))
return res.status(404).send(`Cannot find field "${queryMain}" in ${req.packageSpec} package config`)
mainFilename = packageConfig[queryMain]
} else {
if (typeof packageConfig.unpkg === 'string') {
// The "unpkg" field allows packages to explicitly declare the
// file to serve at the bare URL (see #59).
mainFilename = packageConfig.unpkg
} else if (typeof packageConfig.browser === 'string') {
// Fall back to the "browser" field if declared (only support strings).
mainFilename = packageConfig.browser
} else {
// If there is no main, use "index" (same as npm).
mainFilename = packageConfig.main || 'index'
}
}
resolveFile(path.join(req.packageDir, mainFilename), true, function (error, file, stats) {
if (error)
console.error(error)
if (file == null) {
res.status(404).send(`Cannot find main file "${mainFilename}" in package ${req.packageSpec}`)
} else {
req.file = file.replace(req.packageDir, '')
req.stats = stats
next()
}
})
}
}
module.exports = findFile