如果事件被觸發，您真正缺少的是超時回調的失效。mouseLeave為此，您需要保留返回的setTimeout值以便clearTimeout在計時器到期之前調用（或者如果組件卸載?。。?/p>
以下是基于類的組件中的基本機制：
state = {
hovered: false
};
timer;
mouseEnterHandler = () => this.setState({ hovered: true });
mouseLeaveHandler = () => this.setState({ hovered: false });
onTimeout = () => {
// Do action
};
clearTimer = () => {
clearTimeout(this.timer);
};
// Here's the meat:
// If state updates, then componentDidUpdate is called,
// if the new hovered state is true, set timeout and save the
// returned reference, else clear the timeout using the saved
// timer reference.
componentDidUpdate() {
const { hovered } = this.state;
if (hovered) {
this.timer = setTimeout(this.onTimeout, 500);
} else {
this.clearTimer();
}
}
// This is component cleanup, if the component unmounts before
// the timer expires you may not want the "Do action" to fire,
// so we go ahead and clear the timeout so you're not accidentally
// accessing state/props of an unmounted component.
componentWillUnmount() {
this.clearTimer();
}
以下是等效的功能組件邏輯：
const [hovered, sethovered] = useState(false);
const mouseEnterHandler = () => sethovered(true);
const mouseLeaveHandler = () => sethovered(false);
const onTimeout = () => {
// Do action
};
useEffect(() => {
const timer = hovered && setTimeout(onTimeout, 500);
return () => {
clearTimeout(timer);
};
}, [hovered]);
