diff --git a/middleware/redirects/language-code-redirects.js b/middleware/redirects/language-code-redirects.js index 58bbef5aea..74a37f92ba 100644 --- a/middleware/redirects/language-code-redirects.js +++ b/middleware/redirects/language-code-redirects.js @@ -1,18 +1,37 @@ import languages from '../../lib/languages.js' +const redirectPatterns = Object.values(languages) + .map((language) => language.redirectPatterns || []) + .flat() +// If the enabled languages have `.redirectPatterns`, combine them +// into one which we only need to use to determine if we should bother +// doing the redirect at all. +const combinedRedirectPatternRegex = + redirectPatterns.length > 0 + ? new RegExp(redirectPatterns.map((rex) => rex.source).join('|')) + : null + // This middleware handles redirects for mistyped language codes // // Examples: // /jp* -> /ja* // /zh-TW* -> /cn* export default function languageCodeRedirects(req, res, next) { - for (const code in languages) { - const language = languages[code] - const redirectPatterns = language.redirectPatterns || [] - for (const i in redirectPatterns) { - const redirectPattern = redirectPatterns[i] - if (redirectPattern.test(req.path)) { - return res.redirect(301, req.path.replace(redirectPattern, `/${language.code}`)) + // Only in the unlikely event that the `req.path` starts with one of these + // prefixes do we bother looking up what the redirect should be. + if ( + !req.path.startsWith('/_next/static') && + combinedRedirectPatternRegex && + combinedRedirectPatternRegex.test(req.path) + ) { + // This loop is almost never ever used to it doesn't have to be + // particularly smart or fast. + for (const language of Object.values(languages)) { + const redirectPatterns = language.redirectPatterns || [] + for (const redirectPattern of redirectPatterns) { + if (redirectPattern.test(req.path)) { + return res.redirect(301, req.path.replace(redirectPattern, `/${language.code}`)) + } } } }