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docs/middleware/redirects/language-code-redirects.js
Peter Bengtsson e3fda9943f more efficient language redirectPatterns middleware (#23412)
* more efficient language redirectPatterns middleware

Part of #1322

* feedbacked
2021-12-07 13:32:27 +00:00

41 lines
1.4 KiB
JavaScript

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) {
// 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}`))
}
}
}
}
return next()
}