52c3842d99deee066ada1872b3746eb07b2e314d
[vchess.git] / utils / language.js
1 // Select a language based on browser preferences, or cookie
2 module.exports = function(req, res)
3 {
4 // If preferred language already set:
5 if (!!req.cookies["lang"])
6 return req.cookies["lang"];
7
8 // Else: search and set it
9 const supportedLang = ["en","es","fr"];
10 const langString = req.headers["accept-language"];
11 let langArray = langString
12 .replace(/;q=[0-9.]+/g, "") //priority
13 .replace(/-[A-Z]+/g, "") //region (skipped for now...)
14 .split(",") //may have some duplicates, but removal is too costly
15 let bestLang = "en"; //default: English
16 for (let lang of langArray)
17 {
18 if (supportedLang.includes(lang))
19 {
20 bestLang = lang;
21 break;
22 }
23 }
24 // Cookie expires in 183 days (expressed in milliseconds)
25 res.cookie('lang', bestLang, { maxAge: 183*24*3600*1000 });
26 return bestLang;
27 }