Javascript 设置后如何更改tinyMCE方向性

我想在下拉更改时更改tinyMCE的方向性：

    $('.ddlLanguage').change(function () {
        setLanguage();
    });
    function setLanguage() {
        var lang = $('.ddlLanguage').val()
        if ((lang == "En") || (lang == "Ru") || (lang == "Tr")) {
            tinymce.settings['directionality'] = 'ltr';
        };
        if ((lang == "Ar") || (lang == "Fa")) {
            tinymce.settings['directionality'] = 'rtl';
        };
    };
    $(document).ready(function () {
            setLanguage();
    });

它在页面加载时设置方向性，但在第一次加载后不会更改方向性

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任何帮助都将不胜感激。

我已经删除并重新启动了它，它解决了我的问题：

      function tinyInit(tinyDir) {
            tinymce.init({
                selector: ".txaContent",
                theme: "modern",
                plugins: [
                    "advlist autolink lists link image charmap print preview hr anchor pagebreak",
                    "searchreplace wordcount visualblocks visualchars code fullscreen",
                    "insertdatetime media nonbreaking save table contextmenu directionality",
                    "emoticons template paste textcolor colorpicker textpattern"
                ],
                toolbar1: "insertfile undo redo | styleselect | bold italic | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | link image",
                toolbar2: "print preview media | forecolor backcolor emoticons | ltr rtl",
                image_advtab: true,
                directionality: tinyDir
     };

     function setLanguage() {
        var lang = $('.ddlLanguage').val()
        if ((lang == "En") || (lang == "Ru") || (lang == "Tr")) {
            tinymce.remove();
            tinyInit("ltr");
        };
        if ((lang == "Ar") || (lang == "Fa")) {
            tinymce.remove();
            tinyInit("rtl");
        };
    };