Fallback scheme

[peterver]

How would i go about the following,

I have the following locales defined (en.json, nl.json, fr.json), If a user pops up using Accept-Language nl-BE it will fallback to en due to it being the default language.

How do i make it so that nl-BE (iso 639-4) falls back to the language code nl ? Do i use the modes array for this ?

[alexc101]

I found a solution:

 modes: [
        function () {
            let locale = this.getLocaleFromHeader();
            // if locale undefined set to default
            if(!locale) return 'en';
            // if locale ('en-GB' || 'en-US' etc return 'en')
            if(locale.length > 2) locale = locale.slice(0, 2);

            return locale;
        }
    ]

Not sure if advisable to do like this?