What is the most 'pure javascript' way to write my function? (to reduce the execution time) :     var AcceptLngs = ['de', 'en', 'es', 'fr', 'it', 'pt', 'pt-BR'],
        _getI18N = { 
            'wordToTranslate' : {
                'pt' : `translatedWord`,
                [...]
            },
            '2ndWordToTranslate' : {
                'pt-BR' : `translatedWord`,
                [...]
             }
        },
        nav = window.navigator,
        navLng = nav.language || nav.browserLanguage || nav.userLanguage,
        defaultLng = 'en',
        lng = navLng, //It must be set for translation
    
        // CHECK THE LANGUAGE OF THE NAVIGATOR.
        checkLng = function checkLng() {
            // isL10nAvailable:
            if (AcceptLngs.indexOf(lng) < -1) {
                lng = lng;
                return lng;
            }
        },
        // SEARCH IF LANGUAGE OF THE APP IS AVAILABLE.
        isLngDispo = function isLngDispo() {
            // isSubstrL10nAvailable:
            checkLng();
            if (AcceptLngs.indexOf(lng) === -1) {
                lng = lng.substring(0,2);
                return lng;
            }
        },
        // SEARCH IF LANGUAGE OF THE APP IS AVAILABLE.
        setLng = function setLng() {
            // isL10nNoAvailable:
            isLngDispo();
            if (AcceptLngs.indexOf(lng) === -1) {
                lng = defaultLng;
                return lng;
            }
        };
        // APPLYING LANGUAGE FOR THE APP.
        setLng();


I am beginner in javascript (it shows, isn't it?).
My script works. The problem is its execution time.
I go from 102 ms (without the translation) to 448 ms (with).

I have try with loop, but I didn't manage to make it work properly. He didn't detect the language in `AcceptedLng` and automatically put me the nav.language.

Perhaps, more simply, I should search directly in '_getI18N', but I have not yet gotten familiar with the search in the arrays, and I can not get any results either.

Info: To translate, I use   _getI18N[`wordToTranslate`][lng]  into my script.

Thanks in advance.

