Window Scroll simple

// utils/useDeviceDetect.js
import React from "react";

export default function useDeviceDetect() {
  const [isMobile, setMobile] = React.useState(false);

  React.useEffect(() => {
    const userAgent =
      typeof window.navigator === "undefined" ? "" : navigator.userAgent;
    const mobile = Boolean(
      userAgent.match(
        /Android|BlackBerry|iPhone|iPad|iPod|Opera Mini|IEMobile|WPDesktop/i
      )
    );
    setMobile(mobile);
  }, []);

  return { isMobile };
}

import { useState, useEffect, useRef } from "react";
export default function App() {
  const [day, setDay] = useState("Monday");
  const prevDay = usePrevious(day);
  const getNextDay = () => {
    if (day === "Monday") {
      setDay("Tuesday")
    } else if (day === "Tuesday") {
      setDay("Wednesday")
    } else if (day === "Wednesday") {
      setDay("Thursday")
    } else if (day === "Thursday") {
      setDay("Friday")
    } else if (day === "Friday") {
      setDay("Monday")
    }
  }
  return (
    <div style={{padding: "40px"}}>
      <h1>
        Today is: {day}<br />
        {
          prevDay && (
            <span>Previous work day was: {prevDay}</span>
          )
        }
      </h1>
      <button onClick={getNextDay}>
        Get next day
      </button>
    </div>
  );
}
function usePrevious(val) {
  const ref = useRef()

  useEffect(() => {
    ref.current = val
  }, [val])
  return ref.current
}

import { useState } from "react"

export default function useToggle(defaultValue) {
  const [value, setValue] = useState(defaultValue)

  function toggleValue(value) {
    setValue(currentValue =>
      typeof value === "boolean" ? value : !currentValue
    )
  }

  return [value, toggleValue]
}

const [scroll, setScroll] = useState(false);
 useEffect(() => {
   window.addEventListener("scroll", () => {
     setScroll(window.scrollY > 500);
   });
 }, []);

// Se implementa asi
<div className={scroll ? "box-buscador is--fixed" : "box-buscador"}>

const [scroll, setScroll] = useState(false);
 useEffect(() => {
   window.addEventListener("scroll", () => {
     setScroll(window.scrollY > 50);
   });
 }, []);


className={scroll ? "bg-black" : "bg-white"}

func scrollToBottom(){
    DispatchQueue.main.async {
        let indexPath = IndexPath(row: self.dataArray.count-1, section: 0)
        self.tableView.scrollToRow(at: indexPath, at: .bottom, animated: true)
    }
}

<style>
 .spacer {
  height: 100vh;
}

a {
  color: #3d3d3d;
  font-family: Arial, Helvetica, sans-serif;
}
/* The magic one liner that allows for smooth scrolls */
html {
  scroll-behavior: smooth;
}

  /* Removes the animation for users that don't prefer it */
@media screen and (prefers-reduced-motion: reduce) {
	html {
		scroll-behavior: auto;
	}
}
  
 </style>

<h1 id="top"><a href="#middle">Let's go to the middle of the page</a></h1> 

<div class="spacer">
  &nbsp;
</div>

<h1 id="middle"><a href="#bottom">Go to the bottom?</a></h1>

<div class="spacer">
  &nbsp;
</div>

<h1 id="bottom"><a href="#top">Nah, let's go back to the top</a></h1>

#page .page-section {position: sticky!important; top: 0px!important} html {scroll-behavior: smooth} 

Here is the code from this tutorial with a little bit of a shadow to create even more depth between these pages sections. 

#page .page-section {position: sticky!important; top: 0px; box-shadow: 5px 5px 15px rgba(0,0,0,0.8)!important} html {scroll-behavior: smooth}

<script>
  $(".modal__open").click((e) => {
    e.preventDefault();
  	$('html')
    .css({
      'overflow-y': 'hidden'
    })
  })
  
  
  $(".modal__close").click((e) => {
    e.preventDefault();
  	$('html')
    .css({
      'overflow-y': 'scroll'
    })
  })
</script>

<style>
	html, body {
  		overflow-y: hidden;
  	}
</style>

<script>
  $(function(){
  setTimeout(function(){
    $('html')
    .css({
      'overflow-y': 'scroll'
    })
    
  	window.scrollTo(0, 0);
  }, 3000);
});
</script>

    func setScrollView() {
        let contentWidth = topPlayersTableView.layer.frame.width + 20
        scrollView.contentSize = CGSize(width: contentWidth, height: scrollView.frame.height)
        scrollView.isPagingEnabled = true
    }