I'm messing around with touch events on a touch slider and I keep getting the following error:
Ignored attempt to cancel a touchmove event with cancelable=false, for example because scrolling is in progress and cannot be interrupted.
I'm not sure what is causing this problem, I am new to working with touch events and can't seem to fix this problem.
Here is the code handling the touch event:
Slider.prototype.isSwipe = function(threshold) {
return Math.abs(deltaX) > Math.max(threshold, Math.abs(deltaY));
}
Slider.prototype.touchStart = function(e) {
if (this._isSliding) return false;
touchMoving = true;
deltaX = deltaY = 0;
if (e.originalEvent.touches.length === 1) {
startX = e.originalEvent.touches[0].pageX;
startY = e.originalEvent.touches[0].pageY;
this._$slider.on('touchmove touchcancel', this.touchMove.bind(this)).one('touchend', this.touchEnd.bind(this));
isFlick = true;
window.setTimeout(function() {
isFlick = false;
}, flickTimeout);
}
}
Slider.prototype.touchMove = function(e) {
deltaX = startX - e.originalEvent.touches[0].pageX;
deltaY = startY - e.originalEvent.touches[0].pageY;
if(this.isSwipe(swipeThreshold)) {
e.preventDefault();
e.stopPropagation();
swiping = true;
}
if(swiping) {
this.slide(deltaX / this._sliderWidth, true)
}
}
Slider.prototype.touchEnd = function(e) {
var threshold = isFlick ? swipeThreshold : this._sliderWidth / 2;
if (this.isSwipe(threshold)) {
deltaX < 0 ? this.prev() : this.next();
}
else {
this.slide(0, !deltaX);
}
swiping = false;
this._$slider.off('touchmove', this.touchMove).one(transitionend, $.proxy(function() {
this.slide(0, true);
touchMoving = false;
}, this));
}
You can find the actual slider here at this pen.
If you swipe through fast enough it will throw the error and sometimes get stuck in the middle of a swipe. Still can't wrap my head around why it is not working. Any help/insight would be greatly appreciated. Not sure what I am doing wrong.
The event must be cancelable
. Adding an if
statement solves this issue.
if (e.cancelable) {
e.preventDefault();
}
In your code you should put it here:
if (this.isSwipe(swipeThreshold) && e.cancelable) {
e.preventDefault();
e.stopPropagation();
swiping = true;
}
I had this problem and all I had to do is return true
from touchend and the warning went away.
Calling preventDefault
on touchmove
while you're actively scrolling is not working in Chrome. To prevent performance issues, you cannot interrupt a scroll.
Try to call preventDefault()
from touchstart
and everything should be ok.
Please remove e.preventDefault()
, because event.cancelable
of touchmove is false
.
So you can't call this method.
I know this is an old post but I had a lot of issues trying to solve this and I finally did so I wanted to share.
My issue was that I was adding an event listener within the ontouchstart and removing it in the ontouchend functions - something like this
function onTouchStart() {
window.addEventListener("touchmove", handleTouchMove, {
passive: false
});
}
function onTouchEnd() {
window.removeEventListener("touchmove", handleTouchMove, {
passive: true
});
}
function handleTouchMove(e) {
e.preventDefault();
}
For some reason adding it removing it like this was causing this issue of the event randomly not being cancelable. So to solve this I kept the listener active and toggled a boolean on whether or not it should prevent the event - something like this:
let stopScrolling = false;
window.addEventListener("touchmove", handleTouchMove, {
passive: false
});
function handleTouchMove(e) {
if (!stopScrolling) {
return;
}
e.preventDefault();
}
function onTouchStart() {
stopScrolling = true;
}
function onTouchEnd() {
stopScrolling = false;
}
I was actually using React so my solution involved setting state, but I've simplified it for a more generic solution. Hopefully this helps someone!
来源:https://stackoverflow.com/questions/26478267/touch-move-getting-stuck-ignored-attempt-to-cancel-a-touchmove