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useScrollTrigger.js
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Sun, Aug 3, 06:47

useScrollTrigger.js
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import _extends from "@babel/runtime/helpers/esm/extends";
import _objectWithoutPropertiesLoose from "@babel/runtime/helpers/esm/objectWithoutPropertiesLoose";
const _excluded = ["getTrigger", "target"];
import * as React from 'react';
function defaultTrigger(store, options) {
const {
disableHysteresis = false,
threshold = 100,
target
} = options;
const previous = store.current;
if (target) {
// Get vertical scroll
store.current = target.pageYOffset !== undefined ? target.pageYOffset : target.scrollTop;
}
if (!disableHysteresis && previous !== undefined) {
if (store.current < previous) {
return false;
}
}
return store.current > threshold;
}
const defaultTarget = typeof window !== 'undefined' ? window : null;
export default function useScrollTrigger(options = {}) {
const {
getTrigger = defaultTrigger,
target = defaultTarget
} = options,
other = _objectWithoutPropertiesLoose(options, _excluded);
const store = React.useRef();
const [trigger, setTrigger] = React.useState(() => getTrigger(store, other));
React.useEffect(() => {
const handleScroll = () => {
setTrigger(getTrigger(store, _extends({
target
}, other)));
};
handleScroll(); // Re-evaluate trigger when dependencies change
target.addEventListener('scroll', handleScroll, {
passive: true
});
return () => {
target.removeEventListener('scroll', handleScroll, {
passive: true
});
};
// See Option 3. https://github.com/facebook/react/issues/14476#issuecomment-471199055
// eslint-disable-next-line react-hooks/exhaustive-deps
}, [target, getTrigger, JSON.stringify(other)]);
return trigger;
}

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