Change Site Language with JSOM

Hi,

Here is code which can change site language with JSOM :

<script type="text/javascript" charset="utf8" src="/Style%20Library/SPS/jquery-1.11.3.min.js"></script>

<select id='LangSelect' onchange="SetLanguage();"></select>


<script type="text/javascript">


$( document ).ready(function() {
    LoadLanguages();
    setTimeout(GetUpdatedLangulage, 2000);
});

function LoadLanguages()
{
        var call = $.ajax({
            url: _spPageContextInfo.siteAbsoluteUrl + "/_api/Web/Lists/GetByTitle('Languages')/items?" + "$select=Title,Code,ID&$top=5000",
            type: "GET",
            dataType: "json",
            headers: {
                Accept: "application/json;odata=verbose"
            }
        });

        call.done(function (data, textStatus, jqXHR) {
            var option = '';
            for (var i=0;i<data.d.results.length;i++){
               option += '<option value="'+ data.d.results[i].Code + '">' + data.d.results[i].Title + '</option>';
            }
            $('#LangSelect').append(option);
        });
}

function SetLanguageInRegionalSettings()
{
    var context = SP.ClientContext.get_current();

    var web = context.get_web();

    var regionalSettings = web.get_regionalSettings();

    context.load(regionalSettings)

    context.executeQueryAsync(function () {

            var sel = document.getElementById('LangSelect');
            console.log( sel.value );

            regionalSettings.set_localeId(sel.value); //English (UK)
   
            regionalSettings.update();
   
            context.executeQueryAsync(function () {
                console.log("success");
            }, function (sender, args) {
                console.log(args.get_message());
            });
        }, function (sender, args) {
            console.log(args.get_message());
    });
}

function GetUpdatedLangulage()
{
    var context = SP.ClientContext.get_current();
    var web = context.get_web();
    var regionalSettings = web.get_regionalSettings();
    context.load(regionalSettings,  "LocaleId");

    context.executeQueryAsync(function () {

        //Locale Id
        console.log(regionalSettings.get_localeId()); //2057
        var sel = document.getElementById('LangSelect');
        sel.value = regionalSettings.get_localeId();
    }, function (sender, args) {
        console.log(args.get_message());
    });
}


function SetLanguage()
{
    var context = SP.ClientContext.get_current();

    var web = context.get_web();

    //This is important. Wont work otherwise.
    web.set_isMultilingual(true);
   
    var sel = document.getElementById('LangSelect');
    console.log( sel.value );
    web.addSupportedUILanguage(sel.value); //Dutch
   
    //The full list of SharePoint 2013 and SharePoint Online LCIDs is here:
    //https://technet.microsoft.com/en-us/library/ff463597.aspx
   
    web.update();
   
    context.executeQueryAsync(function(){
        console.log("Language Added");
        SetLanguageInRegionalSettings();
    },function(sender,args){
        console.log(args.get_message());
        SetLanguageInRegionalSettings();
    });   
}

</script>