horizontal layout when scroll

Question

I want to have a horizontal layout in my page ... whenever user scrolls the page instead of top-to-bottom layout I want to have left-to-right layout ... with my code on big screens there is empty space after last section and on small screens last section won't appear.

calcBodyHeight();

function calcBodyHeight() {
  const sections = document.querySelectorAll('.section');
  let height = null;
  sections.forEach(section => {
    height += section.offsetWidth;
  })
  document.body.style.height = `${height}px`;
}
const container = document.querySelector('.container');
window.addEventListener('scroll', e => {
  const scroll = window.scrollY;
  container.style.left = `-${scroll}px`;
});

html,
body {
  height: 100%;
}

body {
  overflow-x: hidden;
  overflow-y: auto;
}

.container {
  width: fit-content;
  height: 100vh;
  display: flex;
  position: fixed;
  left: 0;
  top: 0;
}

.container .section {
  width: 100vw;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container .section:nth-child(1) {
  background-color: cornflowerblue;
}

.container .section:nth-child(2) {
  background-color: coral;
}

.container .section:nth-child(3) {
  background-color: lightgreen;
}

.container .section:nth-child(4) {
  background-color: teal;
}

<div class="container">
  <div class="section"></div>
  <div class="section"></div>
  <div class="section"></div>
  <div class="section"></div>
</div>

Answer 1

The problem is that the initial height is missing from the calculation.

Let's take an example:

body.height: 800
body.width: 400

After calcBodyHeight, body height is 1600px (400 * 4) which means we need to have 1200px to scroll (the first 400px already presented). But, since body.height is 800px this leaves us with only 800ox to scroll.

My suggestion is to calculate a bit different

1. Set the body height as section.length * section.height
2. Get the window ratio (width / height)
3. On scroll, scroll according the ratio

calcBodyHeight();
function calcBodyHeight() {
  const height = [...document.querySelectorAll('.section')]
    .reduce((prev, curr) => prev + curr.offsetHeight, 0);
  document.body.style.height = `${height}px`;
}

const container = document.querySelector('.container');
const ratio = window.innerWidth / window.innerHeight;
window.addEventListener('scroll', e => {
  const scroll = window.scrollY * ratio;
  container.style.left = `-${scroll}px`;
});

Demo

calcBodyHeight();
function calcBodyHeight() {
  const height = [...document.querySelectorAll('.section')]
    .reduce((prev, curr) => prev + curr.offsetHeight, 0);
  document.body.style.height = `${height}px`;
}

const container = document.querySelector('.container');
const ratio = window.innerWidth / window.innerHeight;
window.addEventListener('scroll', e => {
  const scroll = window.scrollY * ratio;
  container.style.left = `-${scroll}px`;
});

html,
body {
  height: 100%;
}

body {
  overflow-x: hidden;
  overflow-y: auto;
}

.container {
  width: fit-content;
  height: 100vh;
  display: flex;
  position: fixed;
  left: 0;
  top: 0;
}

.container .section {
  width: 100vw;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container .section:nth-child(1) {
  background-color: cornflowerblue;
}

.container .section:nth-child(2) {
  background-color: coral;
}

.container .section:nth-child(3) {
  background-color: lightgreen;
}

.container .section:nth-child(4) {
  background-color: teal;
}

<div class="container">
  <div class="section"></div>
  <div class="section"></div>
  <div class="section"></div>
  <div class="section"></div>
</div>