[英]Custom Mouse Cursor using React: Uncaught TypeError: Cannot read property 'clientWidth' of null
嗨,我正在尝试在 React 中创建自定义光标。 光标工作正常,但是在几秒钟后滚动或更改页面后,我收到以下错误:未捕获的类型错误:无法读取 null 的属性“clientWidth”。
//follows the cursor
const customRef = React.useRef(null)
React.useEffect(() => {
document.addEventListener('mousemove', (e) => {
const { clientX, clientY } = e
const mouseX = clientX - customRef.current.clientWidth / 2
const mouseY = clientY - customRef.current.clientHeight / 2
customRef.current.style.transform = `translate3d(${mouseX}px, ${mouseY}px, 0)`
})
}, [])
return (
<div className="app-cursor" ref={customRef} />
)
}
export default CustomCursor
这是CSS:
.app-cursor {
z-index: 100;
border-radius: 50%;
width: 60px;
height: 60px;
border: 1px solid rgb(168, 163, 163);
pointer-events: none;
overflow: hidden;
transform: translate3d(0, 0, 0);
position: fixed;
}
任何帮助,将不胜感激。
提前致谢。
您收到错误的原因是因为您添加了事件侦听器但从未将其删除,并且在应用程序的某个点上,您卸载了正在传递 ref 的元素,并且在尝试访问该 ref 时,它不存在.
您需要在useEffect
的清理效果中删除事件侦听useEffect
。
const CustomCursor = () => {
//follows the cursor
const customRef = React.useRef(null)
useEffect(() => {
const onMouseMove = (e) => {
const { clientX, clientY } = e
const mouseX = clientX - customRef.current.clientWidth / 2
const mouseY = clientY - customRef.current.clientHeight / 2
customRef.current.style.transform = `translate3d(${mouseX}px, ${mouseY}px, 0)`
}
// add the event listener
document.addEventListener('mousemove', onMouseMove)
// cleanup function
return () => {
// remove the event listener when the component unmounts
document.removeEventListener('mousemove', onMouseMove)
}
}, [])
return (
<div className="app-cursor" ref={customRef} />
)
}
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