我如何识别 React 中的滑动事件？

Question

I'm currently developing a React app and I want to detect swipe events (left, right) on a div element (on mobile devices).

How do I achieve this without any additional libraries?

Answer 1

@gru's code works great, the only downside is that it also detects a swipe when the user tries to scroll down and moves slightly to the side as well.

My changes makes sure the swipe is only detected when the horizontal movement is greater than the vertical movement:

const distanceX = touchStartX - touchEndX
const distanceY = touchStartY - touchEndY
const isLeftSwipe = distanceX > minSwipeDistance
const isRightSwipe = distanceX < -minSwipeDistance

if (isRightSwipe && Math.abs(distanceX) > distanceY) {
  // add your conditional logic here
} 
if (isLeftSwipe && distanceX > distanceY) {
  // add your conditional logic here
}

Answer 2

Horiziontal swipes (left, right)

This code detects left and right swipe events, without having any impact on usual touch events.

const [touchStart, setTouchStart] = useState(null)
const [touchEnd, setTouchEnd] = useState(null)

// the required distance between touchStart and touchEnd to be detected as a swipe
const minSwipeDistance = 50 

const onTouchStart = (e) => {
  setTouchEnd(null) // otherwise the swipe is fired even with usual touch events
  setTouchStart(e.targetTouches[0].clientX)
}

const onTouchMove = (e) => setTouchEnd(e.targetTouches[0].clientX)

const onTouchEnd = () => {
  if (!touchStart || !touchEnd) return
  const distance = touchStart - touchEnd
  const isLeftSwipe = distance > minSwipeDistance
  const isRightSwipe = distance < -minSwipeDistance
  if (isLeftSwipe || isRightSwipe) console.log('swipe', isLeftSwipe ? 'left' : 'right')
  // add your conditional logic here
}

<div onTouchStart={onTouchStart} onTouchMove={onTouchMove} onTouchEnd={onTouchEnd}/>

Vertical swipes (up, down)

If you need to detect vertical swipes as well (up and down), you can use e.targetTouches[0].clientY (see docs ) in a similar manner.

Answer 3

Excellent solution provided by @gru. I just encapsulated it into a custom hook to be simpler to integrate between different components.

useSwipe.tsx

import {TouchEvent, useState} from "react";

interface SwipeInput {
    onSwipedLeft: () => void
    onSwipedRight: () => void
}

interface SwipeOutput {
    onTouchStart: (e: TouchEvent) => void
    onTouchMove: (e: TouchEvent) => void
    onTouchEnd: () => void
}

export default (input: SwipeInput): SwipeOutput => {
    const [touchStart, setTouchStart] = useState(0);
    const [touchEnd, setTouchEnd] = useState(0);

    const minSwipeDistance = 50;

    const onTouchStart = (e: TouchEvent) => {
        setTouchEnd(0); // otherwise the swipe is fired even with usual touch events
        setTouchStart(e.targetTouches[0].clientX);
    }

    const onTouchMove = (e: TouchEvent) => setTouchEnd(e.targetTouches[0].clientX);

    const onTouchEnd = () => {
        if (!touchStart || !touchEnd) return;
        const distance = touchStart - touchEnd;
        const isLeftSwipe = distance > minSwipeDistance;
        const isRightSwipe = distance < -minSwipeDistance;
        if (isLeftSwipe) {
            input.onSwipedLeft();
        }
        if (isRightSwipe) {
            input.onSwipedRight();
        }
    }

    return {
        onTouchStart,
        onTouchMove,
        onTouchEnd
    }
}

can be integrated in different components like this

1. import useSwipe from "whatever-path/useSwipe";
2. const swipeHandlers = useSwipe({ onSwipedLeft: () => console.log('left'), onSwipedRight: () => console.log('right') });
3. <div {...swipeHandlers}>some swipeable div (or whatever html tag)</div>