CODEWITHSUNDEEP
javascriptreactjsonscroll
Ritcus
Ritcus

Reputation: 63

Not been able to read the value of scrollY

I have been trying to read the value of scrollY (chrome Version 96.0.4664.45 (Official Build) (64-bit)). But it does not seems to work. Here is my code :

import React from "react";

import{useEffect, useState} from "react"


 
export default function Test() {
  const [offset, setOffset] = useState(0);
  const setScroll = () => {
    setOffset(window.scrollY);
  };

    useEffect(() => {
    window.addEventListener("scroll", setScroll);
    return () => {
      window.removeEventListener("scroll", setScroll);
    };
  }, []);

  return (
    <div className="App" style={{ height: "1000px" }}>
      <h1>Hello CodeSandbox</h1>
      <div>{offset}</div>
      
    </div>
  );
}

Here is a picture of the output: enter image description here

enter image description here

Upvotes: 1

Views: 108

Answers (1)

jsejcksn
jsejcksn

Reputation: 33701

Here is the same code you provided in your question in a snippet (it works). I simply changed the scroll event target from window to document. See the MDN page for the document scroll event: https://developer.mozilla.org/en-US/docs/Web/API/Document/scroll_event

<div id="root"></div><script src="https://unpkg.com/[email protected]/umd/react.development.js"></script><script src="https://unpkg.com/[email protected]/umd/react-dom.development.js"></script><script src="https://unpkg.com/@babel/[email protected]/babel.min.js"></script>
<script type="text/babel" data-type="module" data-presets="react">

const {useEffect, useState} = React;

function Test () {
  const [offset, setOffset] = useState(0);
  const setScroll = () => setOffset(window.scrollY);

  useEffect(() => {
    document.addEventListener("scroll", setScroll);
    return () => document.removeEventListener("scroll", setScroll);
  }, []);

  return (
    <div style={{ height: "1000px" }}>
      <h1>Hello CodeSandbox</h1>
      <div style={{ position: 'sticky', top: '1rem' }}>{offset}</div>
    </div>
  );
}

ReactDOM.render(<Test />, document.getElementById('root'));

</script>

Upvotes: 1

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