how to use addeventlistener in react code example
Example 1: event listener for functional component
import React, { useEffect } from 'react';
const Component = (props) => {
useEffect(() => {
window.addEventListener('scroll', handleScroll);
});
useEffect(() => {
return () => {
window.removeEventListener('scroll', handleScroll);
};
}, []);
function handleScroll() {
let scrollTop = window.scrollY;
}
return ()
}
Example 2: passing event handler to useEffeect
const App =() => {
const [userText, setUserText] = useState("");
useEffect(() => {
const handleUserKeyPress = event => {
const { key, keyCode } = event;
if (keyCode === 32 || (keyCode >= 65 && keyCode <= 90)) {
setUserText(`${userText}${key}`);
}
};
window.addEventListener("keydown", handleUserKeyPress);
return () => {
window.removeEventListener("keydown", handleUserKeyPress);
};
}, [userText]);
return (
<div>
<h1>Feel free to type!</h1>
<blockquote>{userText}</blockquote>
</div>
);
}
ReactDOM.render(<App />, document.getElementById("root"));
Example 3: react event listener
onClick onContextMenu onDoubleClick onDrag onDragEnd onDragEnter onDragExit
onDragLeave onDragOver onDragStart onDrop onMouseDown onMouseEnter onMouseLeave
onMouseMove onMouseOut onMouseOver onMouseUp