iOS/WebKit: touchmove/touchstart not working on in

问题:

I have an IOS Web App that can't be scrolled. For that reason I want to deactivate scrolling. To do this, I use an element's ontouchmove attribute and have it call a function that uses element.preventDefault. However, I am unable to detect any touching event when it starts on a textarea or input element, even when the element is disabled! I have also tried binding the touchmove or touchstart event to these elements via JavaScript's addEventlistener, without success!

And here's my JavaScript:

function onBodyLoad() {

 document.addEventListener( "touchstart", doNotScroll, true );
 document.addEventListener( "touchmove", doNotScroll, true );

}

function doNotScroll( event ) {

 event.preventDefault();
 event.stopPropagation();

}

Thanks for any help!

回答1:

I think I've found a great workaround for this issue using the "pointer-events" CSS property:

function setTextareaPointerEvents(value) {
    var nodes = document.getElementsByTagName('textarea');
    for(var i = 0; i < nodes.length; i++) {
        nodes[i].style.pointerEvents = value;
    }
}

document.addEventListener('DOMContentLoaded', function() {
    setTextareaPointerEvents('none');
});

document.addEventListener('touchstart', function() {
    setTextareaPointerEvents('auto');
});

document.addEventListener('touchmove', function(e) {
    e.preventDefault();
    setTextareaPointerEvents('none');
});

document.addEventListener('touchend', function() {
    setTimeout(function() {
        setTextareaPointerEvents('none');
    }, 0);
});

This will make Mobile Safari on iOS (others not tested so far) ignore the textareas for scrolling but allows to set focus etc. as usual.

回答2:

the Thomas Bachem answer is the one!

I rewrote it in jQuery. Just add a class scrollFix to your desired inputs and you are ready to go. Or attach the event handlers to all inputs and textareas using $('input, textarea').

Now when you touch and scroll on an input on iOS 8+, the input get all its pointer-events disabled (including the problematic behavior). Those pointer-events are enabled when we detect a simple touch.

$('.scrollFix').css("pointer-events","none");

$('body').on('touchstart', function(e) {
    $('.scrollFix').css("pointer-events","auto");
});
$('body').on('touchmove', function(e) {
    $('.scrollFix').css("pointer-events","none");
});
$('body').on('touchend', function(e) {
    setTimeout(function() {
        $('.scrollFix').css("pointer-events", "none");
    },0);
});