const fs = require("fs"); const path = require("path"); const createPackageURL = require("../utils/createPackageURL"); const createSearch = require("./utils/createSearch"); const incrementCounter = require("./utils/incrementCounter"); /** * File extensions to look for when automatically resolving. */ 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((next, ext) => { const file = base + ext; return () => { fs.stat(file, (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, (error, indexFile, indexStats) => { if (error) { callback(error); } else if (indexFile) { callback(null, indexFile, indexStats); } else { next(); } } ); } else { callback(null, file, stats); } }); }; }, callback)(); } function getBasename(file) { return path.basename(file, path.extname(file)); } /** * Find the file targeted by the request and get its stats. Redirect * inexact paths in ?module mode so relative imports resolve correctly. */ function findFile(req, res, next) { let filename = req.filename; let useIndex = true; if (req.query.module != null) { // They want an ES module. if (!filename) { // See https://github.com/rollup/rollup/wiki/pkg.module filename = req.packageConfig.module || req.packageConfig["jsnext:main"] || "/"; } } else if (filename) { // They are requesting an explicit filename. Only try to find an // index.js if they are NOT requesting an HTML directory listing. useIndex = filename.charAt(filename.length - 1) !== "/"; } else if ( req.query.main && typeof req.packageConfig[req.query.main] === "string" ) { // They specified a custom ?main field. // Deprecated, see https://github.com/unpkg/unpkg/issues/63 filename = req.packageConfig[req.query.main]; // Count which packages are using this so we can warn them when we // remove this functionality. incrementCounter( "package-json-custom-main", req.packageSpec + "?main=" + req.query.main, 1 ); } else if (typeof req.packageConfig.unpkg === "string") { // The "unpkg" field allows packages to explicitly declare the // file to serve at the bare URL. filename = req.packageConfig.unpkg; } else if (typeof req.packageConfig.browser === "string") { // Fall back to the "browser" field if declared (only support strings). // Deprecated, see https://github.com/unpkg/unpkg/issues/63 filename = req.packageConfig.browser; // Count which packages + versions are actually using this fallback // so we can warn them when we deprecate this functionality. incrementCounter("package-json-browser-fallback", req.packageSpec, 1); } else { // Fall back to "main" or / (same as npm). filename = req.packageConfig.main || "/"; } resolveFile( path.join(req.packageDir, filename), useIndex, (error, file, stats) => { if (error) console.error(error); if (file == null) { return res .status(404) .type("text") .send( `Cannot find module "${filename}" in package ${req.packageSpec}` ); } filename = file.replace(req.packageDir, ""); if ( req.query.main != null || getBasename(req.filename) !== getBasename(filename) ) { // Need to redirect to the module file so relative imports resolve // correctly. delete req.query.main; // Cache module redirects for 1 minute. res .set({ "Cache-Control": "public, max-age=60", "Cache-Tag": "redirect,module-redirect" }) .redirect( 302, createPackageURL( req.packageName, req.packageVersion, filename, createSearch(req.query) ) ); } else { req.filename = filename; req.stats = stats; next(); } } ); } module.exports = findFile;