モーダルウィンドウ表示用Javascript覚書

    var scrollPosition;
    function toggleSpmenu() {
      var modal = document.getElementById('modal');
      var togglebtn = document.getElementById('togglebtn');
      var modalbg = document.getElementById('modalbg');

      if (modal.classList.contains('show')) {
        /*CLOSE*/
        modal.classList.add('hidden')
        modal.classList.remove('show')
        togglebtn.classList.remove('active');
        modalbg.classList.add('show');
        modalbg.classList.remove('hidden');
        document.body.classList.remove('fixed');
        window.scrollTo(0,scrollPosition);
      } else {
        /*OPEN*/
        scrollPosition = document.documentElement.scrollTop || document.body.scrollTop
        modal.classList.remove('hidden')
        modal.classList.add('show')
        modalbg.classList.remove('show');
        modalbg.classList.add('hidden');
        togglebtn.classList.add('active')
        document.body.classList.add('fixed');
        document.body.style.top = (scrollY * -1) + 'px';
      }

    }