function js_login() {

    //Get items
    var tb_username = document.getElementById('tb_username');
    var tb_password = document.getElementById('tb_password');
    var login_form = document.getElementById('login_form');
    var login_form_username = document.getElementById('login_form_username');
    var login_form_password = document.getElementById('login_form_password');

    //Check
    if (tb_username && tb_password && login_form && login_form_username && login_form_password) {

        //Set values
        login_form_username.value = tb_username.value;
        login_form_password.value = tb_password.value;

        //submit
        login_form.submit();
    
    } else {
        alert("fout!")
    }
}