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Re: ontouch onclick and ios

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On Thu, 03 Nov 2011 16:11:40 +1100, Andrew Poulos wrote:

>I have this in a page
>
>function touchStart(event) {
>   event.preventDefault();
>
>   // more code here...
>}
>
>window.ontouchstart = touchStart;
>
>What I don't understand is:
>- why the preventDefault on line 2 also kills the onclick event on iOS

There is no click when you touch an element, but after you touch (i.e.
touchStart followed by touchRelease) the browser generates a click event
so that touches have the same effect as mouse clicks, when that is
appropriate.

>- why preventDefault is needed

I don't know what your code is doing exactly, but this is often used for
allowing you to touch a menu that normally drops down on hover, so that
you can drop down the menu without it generating a click event and thus
activating the link in the menu. Albeit, it would probably be better to
only prevent the click on first touch, e.g. (assuming dropdowns is a
collection of menu links with child menus):

function menuTouch(event) {
    // toggle flag for preventing click for this link
    var i, len, noclick = !(this.dataNoclick);

    // reset flag on all links
    for (i = 0, len = dropdowns.length; i < len; ++i) {
        dropdowns[i].dataNoclick = false;
    }

    // set new flag value and focus on dropdown menu
    this.dataNoclick = noclick;
    this.focus();
}

function menuClick(event) {
    // if click isn't wanted, prevent it
    if (this.dataNoclick) {
        event.preventDefault();
    }
}

for (i = 0, len = dropdowns.length; i < len; ++i) {
    element = dropdowns[i];
    element.dataNoclick = false;
    element.addEventListener("touchstart", menuTouch, false);
    element.addEventListener("click", menuClick, false);
}

Of course, designing the website to not require such manoeuvres would be
even better :)
-- 
Ross McKay, Toronto, NSW Australia
"The chief cause of problems is solutions" -Eric Sevareid

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Thread

ontouch onclick and ios Andrew Poulos <ap_prog@hotmail.com> - 2011-11-03 16:11 +1100
  Re: ontouch onclick and ios Andrew Poulos <ap_prog@hotmail.com> - 2011-11-03 18:02 +1100
    Re: ontouch onclick and ios Ross McKay <au.org.zeta.at.rosko@invalid.invalid> - 2011-11-03 18:15 +1100
  Re: ontouch onclick and ios Ross McKay <au.org.zeta.at.rosko@invalid.invalid> - 2011-11-03 18:05 +1100
  Re: ontouch onclick and ios David Mark <dmark.cinsoft@gmail.com> - 2011-11-03 07:37 -0700

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