molochnyk

.elementHidden{
  border: none;
  clip: rect(0 0 0 0);
  height: 1px;
  margin: -1px;
  overflow: hidden;
  padding: 0;
  position: absolute;
  width: 1px;
}

molochnyk

<script>
  $("form.form").submit(function () {
		let th = $(this);

		let inputNumber = th.find('input[name=tel]').val();
    if(inputNumber.length < 17) return false;

		th.find('button[type="submit"]').attr('disabled', 'true');
		
    $.ajax({

molochnyk

	function sliceWords() {
		let line = document.querySelectorAll('.secten_block_items_doc p');
		function cutWords(str, max = 20) {
			str.forEach((el) => {
				if(el.textContent.length > max) {
					let string = el.textContent.trim().split(' ').slice(0, max).join() + ' ...';
					el.innerHTML = string;
				}
			})
			return str

molochnyk

 HTML code
 <div class="top" title="Наверх">
    <i class="fa fa-angle-double-up"></i>
  </div>
  
 CSS(SCSS) code
 .top{
  position: fixed;
  bottom: 25px;
  right: -100px;

molochnyk

$(document).ready(function() {
  function heightDetect(){
    $('.main_head').css('height', $(window).height());
  };
    heightDetect();
  
    $(window).resize(function(){
    heightDetect();
  })
}); //endReady