Get website language in javascript

odoo.define('m​odule_name.module', function(require){

start: function() {

    const lang = t​his._getLanguages();​

},

_getLanguages: function () {
    var self = this;
    var context;
    this.trigger_up('context_get', {
        callback: function (ctx) {
            context = ctx;
        },​
    });
    return context.lang
},
});