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加载更多 (Load More Content)

 Remove EventListener after adding 

In React, it is important to remove eventListener after this component is unmounted.

1) Otherwise it might still been called on an unmounted object, then result in memory leak or error

2) Each time, the dependency changes, it might adds eventListener multiple times


Correct example:

useEffect(() => {
if (haveMoreData) {
window.addEventListener("scroll", tryLoadMore);
}
return () => {
window.removeEventListener("scroll", tryLoadMore);
};
}, [searchParams, haveMoreData]);


Load more Content Implementation

However, we only want to load data when it reaches the bottom.

To implement this, we can use useRef() to bind to a div element.

Then, we can use Element.getBoundingClientRect() to get the relative position it has relative to the screen.









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