fixed block

  if (window.innerWidth > 640) {
    var floatParentNode = document.querySelector('.js-parent');
    var floatNode = document.querySelector('.js-float');
    var valScrollForFixed = floatParentNode.getBoundingClientRect().top + window.pageYOffset - document.querySelector('.js-header').offsetHeight;

    window.addEventListener('scroll', function () {
      if (window.innerHeight > floatNode.offsetHeight) {
        var windowScrollTop = window.pageYOffset;
        var footerTop = document.querySelector('.js-footer').getBoundingClientRect().top + windowScrollTop;
        var footerHeight = document.querySelector('.js-footer').clientHeight;
        var valScrollForAbs = windowScrollTop + floatNode.offsetHeight + document.querySelector('.js-header').offsetHeight + 20;

        if (valScrollForAbs >= footerTop) {
          // floatNode.classList.remove('fixed');
          floatNode.classList.add('fixed-footer');
          floatNode.style.bottom = -(document.body.clientHeight - windowScrollTop - window.innerHeight - footerHeight - 20) + 'px';
        } else {
          floatNode.classList.remove('fixed-footer');
          floatNode.style.bottom = '';

          if (windowScrollTop >= valScrollForFixed) {
            floatNode.classList.add('fixed');
          } else {
            floatNode.classList.remove('fixed');
          }
        }
      }
    })
  }