如何检测用户用JavaScript在网页上向某个方向滑动手指?
我想知道是否有一种解决方案可以同时适用于iPhone和Android手机上的网站。
如何检测用户用JavaScript在网页上向某个方向滑动手指?
我想知道是否有一种解决方案可以同时适用于iPhone和Android手机上的网站。
当前回答
简单的水平滑动JS示例:
let touchstartX = 0
let touchendX = 0
function checkDirection() {
if (touchendX < touchstartX) alert('swiped left!')
if (touchendX > touchstartX) alert('swiped right!')
}
document.addEventListener('touchstart', e => {
touchstartX = e.changedTouches[0].screenX
})
document.addEventListener('touchend', e => {
touchendX = e.changedTouches[0].screenX
checkDirection()
})
垂直滑动也可以使用相同的逻辑。
其他回答
我之前使用的方法是,您必须检测mousedown事件,记录其x,y位置(任何相关的位置),然后检测mouseup事件,并减去两个值。
在这里的建议之上,我将跟踪手指号码,因为如果你同时用两个手指触摸,它将获得X位置,而不会导致一个奇怪的行为,而且,你可能想要设置一个“距离”最小值,这样用户在通过你的网站或应用程序触摸时就不会错误地触发滑动。
//Swipe
let touchstartX = 0
let touchendX = 0
let fingerCount = 0
const checkDirection = () => {
const distance = 50 //Minimum distance for the swipe to work
//left
if (touchendX < touchstartX && (touchstartX - touchendX) > distance ){
//Do something cool
}
//right
if (touchendX > touchstartX && (touchendX - touchstartX) > distance){
//Do something cooler
}
document.addEventListener('touchstart', e => {
fingerCount = e.touches.length
touchstartX = e.changedTouches[0].clientX
})
document.addEventListener('touchend', e => {
touchendX = e.changedTouches[0].clientX
if(fingerCount === 1){
checkDirection()
}
})
一个如何使用偏移量的例子。
// at least 100 px are a swipe // you can use the value relative to screen size: window.innerWidth * .1 const offset = 100; let xDown, yDown window.addEventListener('touchstart', e => { const firstTouch = getTouch(e); xDown = firstTouch.clientX; yDown = firstTouch.clientY; }); window.addEventListener('touchend', e => { if (!xDown || !yDown) { return; } const { clientX: xUp, clientY: yUp } = getTouch(e); const xDiff = xDown - xUp; const yDiff = yDown - yUp; const xDiffAbs = Math.abs(xDown - xUp); const yDiffAbs = Math.abs(yDown - yUp); // at least <offset> are a swipe if (Math.max(xDiffAbs, yDiffAbs) < offset ) { return; } if (xDiffAbs > yDiffAbs) { if ( xDiff > 0 ) { console.log('left'); } else { console.log('right'); } } else { if ( yDiff > 0 ) { console.log('up'); } else { console.log('down'); } } }); function getTouch (e) { return e.changedTouches[0] }
函数检查水平方向和垂直方向,以确定哪个滑动更长,以防止执行两个指令,因为不可能进行完美的单向滑动。滑动总是在X和Y上有偏差。
let touchstartX = 0;
let touchendX = 0;
let touchstartY = 0;
let touchendY = 0;
function checkDirection() {
let difX = touchstartX - touchendX;
let difY = touchstartY - touchendY;
if (Math.abs(difX) > Math.abs(difY)) {
if (touchendX < touchstartX) {/*left*/}
if (touchendX > touchstartX) {/*right*/}
} else {
if (touchendY < touchstartY) {/*up*/}
if (touchendY > touchstartY) {/*down*/}
}
};
document.addEventListener('touchstart', e => {
e.preventDefault();
touchstartX = e.changedTouches[0].screenX;
touchstartY = e.changedTouches[0].screenY;
});
document.addEventListener('touchend', e => {
e.preventDefault();
touchendX = e.changedTouches[0].screenX;
touchendY = e.changedTouches[0].screenY;
checkDirection();
});
我重做了@givanse的解决方案,使其发挥React钩子的作用。输入是一些可选的事件监听器,输出是一个功能性的ref(需要是功能性的,以便当/如果ref改变时钩子可以重新运行)。
还添加了垂直/水平滑动阈值参数,这样小的运动不会意外触发事件监听器,但这些可以设置为0,以更接近地模拟原始答案。
提示:为了获得最佳性能,应该记住事件侦听器输入函数。
function useSwipeDetector({
// Event listeners.
onLeftSwipe,
onRightSwipe,
onUpSwipe,
onDownSwipe,
// Threshold to detect swipe.
verticalSwipeThreshold = 50,
horizontalSwipeThreshold = 30,
}) {
const [domRef, setDomRef] = useState(null);
const xDown = useRef(null);
const yDown = useRef(null);
useEffect(() => {
if (!domRef) {
return;
}
function handleTouchStart(evt) {
const [firstTouch] = evt.touches;
xDown.current = firstTouch.clientX;
yDown.current = firstTouch.clientY;
};
function handleTouchMove(evt) {
if (!xDown.current || !yDown.current) {
return;
}
const [firstTouch] = evt.touches;
const xUp = firstTouch.clientX;
const yUp = firstTouch.clientY;
const xDiff = xDown.current - xUp;
const yDiff = yDown.current - yUp;
if (Math.abs(xDiff) > Math.abs(yDiff)) {/*most significant*/
if (xDiff > horizontalSwipeThreshold) {
if (onRightSwipe) onRightSwipe();
} else if (xDiff < -horizontalSwipeThreshold) {
if (onLeftSwipe) onLeftSwipe();
}
} else {
if (yDiff > verticalSwipeThreshold) {
if (onUpSwipe) onUpSwipe();
} else if (yDiff < -verticalSwipeThreshold) {
if (onDownSwipe) onDownSwipe();
}
}
};
function handleTouchEnd() {
xDown.current = null;
yDown.current = null;
}
domRef.addEventListener("touchstart", handleTouchStart, false);
domRef.addEventListener("touchmove", handleTouchMove, false);
domRef.addEventListener("touchend", handleTouchEnd, false);
return () => {
domRef.removeEventListener("touchstart", handleTouchStart);
domRef.removeEventListener("touchmove", handleTouchMove);
domRef.removeEventListener("touchend", handleTouchEnd);
};
}, [domRef, onLeftSwipe, onRightSwipe, onUpSwipe, onDownSwipe, verticalSwipeThreshold, horizontalSwipeThreshold]);
return (ref) => setDomRef(ref);
};