express-bcp47 -- middleware for parsing locale from headers

SYNOPSIS

var bcp47mw = require('express-bcp47');
app.use(bcp47mw({ defaultLocale: "en-US", vary: true }));

DESCRIPTION

express-bcp47 is a simple middleware that parses the Accept-Language header from the browser and exposes it to handlers under req.locale (for handlers) and res.locals.locale (for the view layer)

There are three parameters to the options object used in the constructor:

• defaultLocale, a string in bcp47 format for the locale to use when the browser does not send one
• acceptLocales, an array of strings in bcp47 format to match up to what the user's browser sends and find a matching locale.
• vary, a boolean (defaults to false) that has the middleware send back the Vary: Accept-Language header, to signal that content for this resource varies depending on that header, improving cacheability. Turn this on if you don't set the Vary header yourself dependent on other values like Cookie or Accept-Type in addition to Accept-Language