sencha extjs 6 - load locale dynamically

gistfile1.js

function loadLocale(){

    var query = Ext.Object.fromQueryString(location.search),
        lang = query.lang ? query.lang.toLowerCase() : 'en';

    if (lang === 'pt'){
        lang = 'pt_BR';
    }

    var extJsFile = Ext.util.Format.format("resources/locale/ext-locale-{0}.js", lang);
    if (lang !== 'en'){
        Ext.Loader.loadScript({url: extJsFile});
    }
}

loadLocale();