Aleksey Solovyev

first.addEventListener('change', function(e) {
  ....
});

first.addEventListener('change', function(e) {
  // this.value - значение первого select'а
  second.querySelector('option[value=' + this.value + ']').selected = 'selected'
});

console.log(li, "li"); // array of elements "li"
for (var i = li.length - 1; i >= 0; i--) {
	console.log(li[i], "li[i]"); // element with sequence number "i" in array "li"
	console.log(li[i].getElementsByTagName('a'), "li[i].getElementsByTagName('a')"); // all <a> - elements in li[i]
	console.log(li[i].getElementsByTagName('a')[0], "li[i].getElementsByTagName('a')[0]"); // first <a> - element in li[i]
	let a = li[i].getElementsByTagName('a')[0];
}

const images = document.querySelectorAll('img');

images.forEach(function(img){
  // get image width: 'w' and height: 'h'
  // get list-product-item__img width: containerW, height: containerH
  // .....
  const imgAspect = w/h;
  const containerAspect = containerW/containerH;

	if (containerAspect>imgAspect) {
    // set image width and height
		img.style.width = containerW;
		img.style.height = containerW / imgAspect;
	} else {
    // set image width and height
		img.style.height = containerH;
		img.style.width = containerH * imgAspect;
	}
})

.image{
  /* ваши стили */
  
  /* сдвигаем на 100px вниз и задаем прозрачность 0*/
  transform: translate3d(0, 100px, 0);
  opacity: 0;
  /* ******* */
  
  transition: opacity .3s, transform .3s;
}
.image.is-shown{
  /* возвращаем в обычное состояние */
  transform: translate3d(0, 0px, 0);
  opacity: 1;
}

const image = document.getElementById('image');
const imageFromTop = image.getBoundingClientRect().top;

const showOnScroll = debounce(function() {
	// How much scroll from top
	let scrollTop = (window.pageYOffset !== undefined) ? window.pageYOffset : (document.documentElement || document.body.parentNode || document.body).scrollTop;
	// Check scroll position
	if (imageFromTop < scrollTop + 500) {
		image.classList.add('is-shown')

		// Remove this listener for better pref
		window.removeEventListener('scroll', showOnScroll, false);
	}
}, 30);

window.addEventListener('scroll', showOnScroll, false);

function debounce(func, wait, immediate) {
	var timeout;
	return function() {
		var context = this, args = arguments;
		var later = function() {
			timeout = null;
			if (!immediate) func.apply(context, args);
		};
		var callNow = immediate && !timeout;
		clearTimeout(timeout);
		timeout = setTimeout(later, wait);
		if (callNow) func.apply(context, args);
	};
};

.cv-image {
  position: relative
}
.img1,
.img2 {
  display: block;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%)
}

const el = document.getElementById('image');
const divOffset = offset(el);
window.onscroll = stay;
function stay() {
  var scrollTop = (window.pageYOffset !== undefined) ? window.pageYOffset : (document.documentElement || document.body.parentNode || document.body).scrollTop;
  el.style.top = divOffset.top + scrollTop + 'px'

}

function offset(el) {
    var rect = el.getBoundingClientRect(),
    scrollLeft = window.pageXOffset || document.documentElement.scrollLeft,
    scrollTop = window.pageYOffset || document.documentElement.scrollTop;
    return { top: rect.top + scrollTop, left: rect.left + scrollLeft }
}

sudo apt install software-properties-common python-software-properties
sudo add-apt-repository ppa:pypa/ppa
sudo apt update
sudo apt install pipenv

sudo apt install python3-pip 
sudo apt install python-pip

--user Install to the Python user install directory for your platform. Typically ~/.local/, or %APPDATA%\Python on
Windows. (See the Python documentation for site.USER_BASE for full details.)

sudo apt-get update && sudo apt-get -y upgrade
sudo apt-get install python3
sudo apt-get install -y python3-pip
pip3 install virtualenv

mkdir django-apps
cd django-apps 
virtualenv env
. env/bin/activate

(env) sammy@ubuntu:$ pip install django
(env) sammy@ubuntu:$ django-admin --version

(env) sammy@ubuntu:$ django-admin startproject app