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

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] }

其他回答

根据@givanse的回答,以下是你可以用类来做的:

class Swipe {
    constructor(element) {
        this.xDown = null;
        this.yDown = null;
        this.element = typeof(element) === 'string' ? document.querySelector(element) : element;

        this.element.addEventListener('touchstart', function(evt) {
            this.xDown = evt.touches[0].clientX;
            this.yDown = evt.touches[0].clientY;
        }.bind(this), false);

    }

    onLeft(callback) {
        this.onLeft = callback;

        return this;
    }

    onRight(callback) {
        this.onRight = callback;

        return this;
    }

    onUp(callback) {
        this.onUp = callback;

        return this;
    }

    onDown(callback) {
        this.onDown = callback;

        return this;
    }

    handleTouchMove(evt) {
        if ( ! this.xDown || ! this.yDown ) {
            return;
        }

        var xUp = evt.touches[0].clientX;
        var yUp = evt.touches[0].clientY;

        this.xDiff = this.xDown - xUp;
        this.yDiff = this.yDown - yUp;

        if ( Math.abs( this.xDiff ) > Math.abs( this.yDiff ) ) { // Most significant.
            if ( this.xDiff > 0 ) {
                this.onLeft();
            } else {
                this.onRight();
            }
        } else {
            if ( this.yDiff > 0 ) {
                this.onUp();
            } else {
                this.onDown();
            }
        }

        // Reset values.
        this.xDown = null;
        this.yDown = null;
    }

    run() {
        this.element.addEventListener('touchmove', function(evt) {
            this.handleTouchMove(evt).bind(this);
        }.bind(this), false);
    }
}

你可以这样使用它:

// Use class to get element by string.
var swiper = new Swipe('#my-element');
swiper.onLeft(function() { alert('You swiped left.') });
swiper.run();

// Get the element yourself.
var swiper = new Swipe(document.getElementById('#my-element'));
swiper.onLeft(function() { alert('You swiped left.') });
swiper.run();

// One-liner.
(new Swipe('#my-element')).onLeft(function() { alert('You swiped left.') }).run();

如果你只需要滑动,你最好只使用你需要的部分。 这应该适用于任何触摸设备。

这是经过gzip压缩,缩小,babel等大约450字节。

我根据其他答案编写了下面的类,它使用移动百分比而不是像素,以及一个事件分派器模式来挂钩/取消挂钩。

像这样使用它:

const dispatcher = new SwipeEventDispatcher(myElement);
dispatcher.on('SWIPE_RIGHT', () => { console.log('I swiped right!') })

export class SwipeEventDispatcher { constructor(element, options = {}) { this.evtMap = { SWIPE_LEFT: [], SWIPE_UP: [], SWIPE_DOWN: [], SWIPE_RIGHT: [] }; this.xDown = null; this.yDown = null; this.element = element; this.options = Object.assign({ triggerPercent: 0.3 }, options); element.addEventListener('touchstart', evt => this.handleTouchStart(evt), false); element.addEventListener('touchend', evt => this.handleTouchEnd(evt), false); } on(evt, cb) { this.evtMap[evt].push(cb); } off(evt, lcb) { this.evtMap[evt] = this.evtMap[evt].filter(cb => cb !== lcb); } trigger(evt, data) { this.evtMap[evt].map(handler => handler(data)); } handleTouchStart(evt) { this.xDown = evt.touches[0].clientX; this.yDown = evt.touches[0].clientY; } handleTouchEnd(evt) { const deltaX = evt.changedTouches[0].clientX - this.xDown; const deltaY = evt.changedTouches[0].clientY - this.yDown; const distMoved = Math.abs(Math.abs(deltaX) > Math.abs(deltaY) ? deltaX : deltaY); const activePct = distMoved / this.element.offsetWidth; if (activePct > this.options.triggerPercent) { if (Math.abs(deltaX) > Math.abs(deltaY)) { deltaX < 0 ? this.trigger('SWIPE_LEFT') : this.trigger('SWIPE_RIGHT'); } else { deltaY > 0 ? this.trigger('SWIPE_UP') : this.trigger('SWIPE_DOWN'); } } } } export default SwipeEventDispatcher;

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);
};

我重做了@ruben-martinez的答案,使用来自@givanse的惊人的解决方案,使用自定义反应钩子处理滑动事件。

import React, { useEffect, useRef, useState } from "react";

export default function useSwiper() {
  const [domRef, setDomRef] = useState<any>();

  const xDown: React.MutableRefObject<number | null> = useRef(null);
  const yDown: React.MutableRefObject<number | null> = useRef(null);

  useEffect(() => {
if (!domRef) return;

function getTouches(event: React.TouchEvent<HTMLDivElement>) {
  return event.touches;
}

function handleTouchStart(event: any) {
  const firstTouch = getTouches(event)[0];
  xDown.current = firstTouch.clientX;
  yDown.current = firstTouch.clientY;
}

function handleTouchMove(event: React.TouchEvent<HTMLDivElement>) {
  if (!xDown.current || !yDown.current) return;

  const firstTouch = getTouches(event)[0];
  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)) {
    // handle horizontal swipes
    if (xDiff > 0) {
      // we swiped right
      console.log("right");
    } else {
      // we swiped left
      console.log("left");
    }
  } else {
    // handle vertical swipes
    if (yDiff > 0) {
      // we swiped down
      console.log("down");
    } else {
      // we swiped up
      console.log("up");
    }
  }
}

function handleTouchEnd(event: React.TouchEvent<HTMLDivElement>) {
  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, false);
    domRef.removeEventListener("touchmove", handleTouchMove, false);
    domRef.removeEventListener("touchend", handleTouchEnd, false);
};
  }, [domRef]);

  return (ref: any) => setDomRef(ref);
}

我在实现他的答案时遇到的主要挑战是不知道如何将swipe元素的ref绑定到自定义钩子中的ref。

基本上,所发生的是我们从自定义钩子返回一个函数。这个函数允许我们传入一个来自我们想要监听的滑动动作的元素的ref。自定义钩子接收到ref后,用元素的ref更新钩子状态,从而触发重新渲染,这样我们就有了实际的元素!

这种函数式的ref样式还允许我们对多个元素使用钩子。如下所示,我想使用它的项目列表,以启用滑动删除:)

import useSwiper from "./hooks/useSwipe";

const EntryCard = ({ entry, godMode, reload }: EntryProps) => {
const swiperRef = useSwiper();

const handleEntryClick =
(entry: Entry) => async (event: React.MouseEvent<HTMLDivElement>) => {
  if (!godMode) return;

  try {
    reload((state) => !state);
  } catch (err) {
    console.log("Error deleting entry: ", err);
  }
};

return (
  <div className="item" onClick={handleEntryClick(entry)} ref={swiperRef}>
    <div className="username">{entry.userName}</div>
    <div className="score">{entry.weekScore}</div>
  </div>
 );
};

PS:你可以把函数传递给钩子来接收滑动值。谢谢:)如果你喜欢,请投票:)

touchStart和touchEnd的句柄:

var handleSwipe = function(elem,callbackOnRight, callbackOnLeft, callbackOnDown, 
      callbackOnUp) => {

        elem.ontouchstart = handleTouchStart;
        elem.ontouchend = handleTouchEnd;

        var xDown = null;
        var yDown = null;

        function getTouches(evt) {
            return evt.touches ||             // browser API
                evt.originalEvent.touches; // jQuery
        }

        function handleTouchStart(evt) {
            const firstTouch = getTouches(evt)[0];
            xDown = firstTouch.clientX;
            yDown = firstTouch.clientY;
        };

        function handleTouchEnd(evt) {
            if (!xDown || !yDown) {
                return;
            }

            var xUp = evt.changedTouches[0].clientX;
            var yUp = evt.changedTouches[0].clientY;

            var xDiff = xDown - xUp;
            var yDiff = yDown - yUp;
            var minDif = 30;

            console.log(`xDiff:${xDiff}, yDiff:${yDiff}`);

            if (Math.abs(xDiff) > Math.abs(yDiff)) {
                if (xDiff > minDif) {
                    if (callbackOnLeft)
                        callbackOnLeft();
                } else if (xDiff < -1 * minDif){
                    if (callbackOnRight)
                        callbackOnRight();
                }
            } else {
                if (yDiff > minDif) {
                    if (callbackOnDown)
                        callbackOnDown();
                } else if (yDiff < -1* minDif){
                    if (callbackOnUp)
                        callbackOnUp();
                }
            }
            
            xDown = null;
            yDown = null;
        };
    }