[jquery] How to bind 'touchstart' and 'click' events but not respond to both?

I'm working on a mobile web site that has to work on a variety of devices. The one's giving me a headache at the moment are BlackBerry.

We need to support both keyboard clicks as well as touch events.

Ideally I'd just use:

$thing.click(function(){...})

but the issue we're running into is that some of these blackberry devices have an very annoying delay from the time of the touch to it triggering a click.

The remedy is to instead use touchstart:

$thing.bind('touchstart', function(event){...})

But how do I go about binding both events, but only firing one? I still need the click event for keyboard devices, but of course, don't want the click event firing if I'm using a touch device.

A bonus question: Is there anyway to do this and additionally accommodate browsers that don't even have a touchstart event? In researching this, it looks like BlackBerry OS5 doesn't support touchstart so will also need to rely on click events for that browser.

ADDENDUM:

Perhaps a more comprehensive question is:

With jQuery, is it possible/recommended to handle both touch interactions and mouse interactions with the same bindings?

Ideally, the answer is yes. If not, I do have some options:

1) We use WURFL to get device info so could create our own matrix of devices. Depending on the device, we'll use touchstart OR click.

2) Detect for touch support in the browser via JS (I need to do some more research on that, but it seems like that is doable).

However, that still leaves one issue: what about devices that support BOTH. Some of the phones we support (namely the Nokias and BlackBerries) have both touch screens and keyboards. So that kind of takes me full circle back to the original question...is there a way to allow for both at once somehow?

You could try something like this:

var clickEventType=((document.ontouchstart!==null)?'click':'touchstart');
$("#mylink").bind(clickEventType, myClickHandler);

This worked for me, mobile listens to both, so prevent the one, which is the touch event. desktop only listen to mouse.

 $btnUp.bind('touchstart mousedown',function(e){
     e.preventDefault();

     if (e.type === 'touchstart') {
         return;
     }

     var val = _step( _options.arrowStep );
               _evt('Button', [val, true]);
  });

find the document scroll move difference (both horizontal and vertical ) touchstart and touchend , if one of them is larger than 1 pixel, then it is move rather than click

var touchstartverscrollpos , touchstarthorscrollpos;


    $('body').on('touchstart','.thumbnail',function(e){

        touchstartverscrollpos = $(document).scrollTop();
        touchstarthorscrollpos = $(document).scrollLeft();


    });



    $('body').on('touchend','.thumbnail',function(e){


        var touchendverscrollpos = $(document).scrollTop();
        var touchendhorscrollpos = $(document).scrollLeft();

        var verdiff = touchendverscrollpos - touchstartverscrollpos;
        var hordiff = touchendhorscrollpos - touchstarthorscrollpos;


        if (Math.abs(verdiff) <1 && Math.abs(hordiff)<1){

// do you own function () here 



            e.stopImmediatePropagation();

            return false;
        }

    });

I had to do something similar. Here is a simplified version of what worked for me. If a touch event is detected, remove the click binding.

$thing.on('touchstart click', function(event){
  if (event.type == "touchstart")
    $(this).off('click');

  //your code here
});

In my case the click event was bound to an <a> element so I had to remove the click binding and rebind a click event which prevented the default action for the <a> element.

$thing.on('touchstart click', function(event){
  if (event.type == "touchstart")
    $(this).off('click').on('click', function(e){ e.preventDefault(); });

  //your code here
});

Another implementation for better maintenance. However, this technique will also do event.stopPropagation (). The click is not caught on any other element that clicked for 100ms.

var clickObject = {
    flag: false,
    isAlreadyClicked: function () {
        var wasClicked = clickObject.flag;
        clickObject.flag = true;
        setTimeout(function () { clickObject.flag = false; }, 100);
        return wasClicked;
    }
};

$("#myButton").bind("click touchstart", function (event) {
   if (!clickObject.isAlreadyClicked()) {
      ...
   }
}

I'm not sure if this works on all browsers and devices. I tested this using Google Chrome and Safari iOS.

$thing.on('click || touchend', function(e){

});

The OR opperand should fire only the first event (on desktop that should be click and on an iPhone that should be touchend).

Well... All of these are super complicated.

If you have modernizr, it's a no-brainer.

ev = Modernizr.touch ? 'touchstart' : 'click';

$('#menu').on(ev, '[href="#open-menu"]', function(){
  //winning
});

I am also working on an Android/iPad web app, and it seems that if only using "touchmove" is enough to "move components" ( no need touchstart ). By disabling touchstart, you can use .click(); from jQuery. It's actually working because it hasn't be overloaded by touchstart.

Finally, you can binb .live("touchstart", function(e) { e.stopPropagation(); }); to ask the touchstart event to stop propagating, living room to click() to get triggered.

It worked for me.

This is the fix that I "create" and it take out the GhostClick and implements the FastClick. Try on your own and let us know if it worked for you.

$(document).on('touchstart click', '.myBtn', function(event){
        if(event.handled === false) return
        event.stopPropagation();
        event.preventDefault();
        event.handled = true;

        // Do your magic here

});

Taking advantage of the fact that a click will always follow a touch event, here is what I did to get rid of the "ghost click" without having to use timeouts or global flags.

$('#buttonId').on('touchstart click', function(event){
    if ($(this).data("already")) {
        $(this).data("already", false);
        return false;
    } else if (event.type == "touchstart") {
        $(this).data("already", true);
    }
    //your code here
});

Basically whenever an ontouchstart event fires on the element, a flag a set and then subsequently removed (and ignored), when the click comes.

I believe the best practice is now to use:

$('#object').on('touchend mouseup', function () { });

touchend

The touchend event is fired when a touch point is removed from the touch surface.

The touchend event will not trigger any mouse events.

mouseup

The mouseup event is sent to an element when the mouse pointer is over the element, and the mouse button is released. Any HTML element can receive this event.

The mouseup event will not trigger any touch events.

EXAMPLE

$('#click').on('mouseup', function () { alert('Event detected'); });
$('#touch').on('touchend', function () { alert('Event detected'); });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h1 id="click">Click me</h1>
<h1 id="touch">Touch me</h1>

EDIT (2017)

As of 2017, browsers starting with Chrome are making steps towards making the click event .on("click") more compatible for both mouse and touch by eliminating the delay generated by tap events on click requests.

This leads to the conclusion that reverting back to using just the click event would be the simplest solution moving forward.

I have not yet done any cross browser testing to see if this is practical.

This hasn't been mentioned here, but you may want to check out this link: https://joshtronic.com/2015/04/19/handling-click-and-touch-events-on-the-same-element/

To recap for posterity, instead of trying to assign to both handlers and then sort out the result, you can simply check if the device is a touchscreen or not and only assign to the relevant event. Observe:

var clickEvent = (function() {
  if ('ontouchstart' in document.documentElement === true)
    return 'touchstart';
  else
    return 'click';
})();

// and assign thusly:

el.addEventListener( clickEvent, function( e ){ 
    // things and stuff
});

I am using this to bind my events so that I can test on touchscreens that handle both touchstart and click events which would fire twice, and on my development PC which only hears the click

One problem the author of that link mentions though, is touchscreen laptops designed to handle both events:

I learned about a third device I was not considering, the touchscreen laptop. It’s a hybrid device that supports both touch and click events. Binding one event means only that event be supported. Does that mean someone with a touchscreen and mouse would have to explicitly touch because that’s the only event I am handling?

Binding touchstart and click seemed ideal to handle these hybrid devices. To keep the event from firing twice, I added e.stopPropagation() and e.preventDefault() to the callback functions. e.stopPropagation() stops events from “bubbling up” to their parents but also keeps a second event from firing. I included e.preventDefault() as a “just in case” but seems like it could be omitted.

For simple features, just recognize touch or click I use the following code:

var element = $("#element");

element.click(function(e)
{
  if(e.target.ontouchstart !== undefined)
  {
    console.log( "touch" );
    return;
  }
  console.log( "no touch" );
});

This will return "touch" if the touchstart event is defined and "no touch" if not. Like I said this is a simple approach for click/tap events just that.

You could try like this:

var clickEvent = (('ontouchstart' in document.documentElement)?'touchstart':'click');
$("#mylink").on(clickEvent, myClickHandler);

Try to use Virtual Mouse (vmouse) Bindings from jQuery Mobile. It's virtual event especially for your case:

$thing.on('vclick', function(event){ ... });

http://api.jquerymobile.com/vclick/

Browser support list: http://jquerymobile.com/browser-support/1.4/

I succeeded by the following way.

Easy Peasy...

$(this).on('touchstart click', function(e){
  e.preventDefault();
  //do your stuff here
});

UDPATE:

I've been working on an implementation to use both click and touchend events for the same function, and the function effectively blocks events if the type changes. My goal was to have a more responsive application interface - I wanted to reduce time for the event start to UI feedback loop.

For this implementation to work, the assumption is that you have all your related events added on 'click' and 'touchend'. This prevents one element from being deprived of event bubbling should both events be required to run, but are of different types.

Here is an lightweight API based implementation that I have simplified for demonstration purposes. It demonstrates how to use the functionality on a collapse element.

var tv = {
    /**
     * @method eventValidator()
     * @desc responsible for validating event of the same type.
     * @param {Object} e - event object
     * @param {Object} element - element event cache
     * @param {Function} callback - callback to invoke for events of the same type origin
     * @param {Object} [context] - context to pass to callback function
     * @param {Array} [args] - arguments array to pass in with context. Requires context to be passed
     * @return {Object} - new event cache
     */
    eventValidator: function(e, element, callback, context, args){
        if(element && element.type && element.type !== e.type){
            e.stopPropagation();
            e.preventDefault();
            return tv.createEventCacheObj({}, true);
        } else {
            element = tv.createEventCacheObj(e);
            (typeof context === "object" ? callback.apply(context, args) : callback());
            return element;
        }
    },

    /**
     * @method createEventCacheObj()
     * @param {Object} event - event object
     * @param {String} [event.type] - event type
     * @param {Number} [event.timeStamp] - time of event in MS since load
     * @param {Boolean} [reset=false] - flag to reset the object
     * @returns {{type: *, time: string}}
     */
    createEventCacheObj: function (event, reset){
        if(typeof reset !== 'boolean') reset = false;
        return {
            type: !reset ? event.type : null,
            time: !reset ? (event.timeStamp).toFixed(2): null
        };
    }
};

// Here is where the magic happens
var eventCache = [];
var pos = 0;

var $collapses = document.getElementsByClassName('tv-collapse__heading');
    Array.prototype.forEach.call($collapses, function(ele){
        ele.addEventListener('click', toggleCollapse);
        ele.addEventListener('touchend', toggleCollapse);

        // Cache mechanism
        ele.setAttribute('data-event-cache', String(pos++));
    });

/**
 * @func toggleCollapse()
 * @param {Object} e - event object
 * @desc responsible for toggling the state of a collapse element
 */
function toggleCollapse(e){
    eventCache[pos] = tv.eventValidator(e, eventCache[pos], function(){
       // Any event which isn't blocked will run the callback and its content
       // the context and arguments of the anonymous function match the event function context and arguments (assuming they are passed using the last two parameters of tv.eventValidator)

    }, this, arguments);
}

Original Answer:

Here is a response which is a modification of Rafael Fragoso's answer - pure JS.

(function(){_x000D_
  _x000D_
  button = document.getElementById('sayHi');_x000D_
  _x000D_
  button.addEventListener('touchstart', ohHai);_x000D_
  button.addEventListener('click', ohHai);_x000D_
_x000D_
  function ohHai(event){_x000D_
    event.stopPropagation();_x000D_
    event.preventDefault();_x000D_
    console.log('ohHai is:', event.type);_x000D_
  };_x000D_
})();

<!DOCTYPE html>_x000D_
<html lang="en">_x000D_
<head>_x000D_
    <meta charset="UTF-8">_x000D_
    <title>SO - Answer</title>_x000D_
</head>_x000D_
<body>_x000D_
  <button id="sayHi">Anyone there?</button>_x000D_
</body>_x000D_
</html>

Run the snippet on the following and pay attention to the output:

• Phone
• Tablet
• Tablet (Desktop Mode - if applicable)
• Desktop
• Desktop (Touch Screen - if applicable)

The key is we are stopping successive events from firing. Mobile browsers do their best to emulate a click when a touch happens. I wish I could find the link to an article a saw a while back that explains all the events that occur after touchstart through click. (I was searching for the 300ms delay between double tap and click actually firing).

Touch and Mouse Devices

I ran a couple of tests using a Surface Pro and a windows 10 desktop with a touchscreen. What I found was that they both triggered events as you would suspect, touchstart for touches and click for trackpad, mouse, and stylist. The interesting thing was that a touch event which was near, but not on the button, would triggering a click event without a touch event. It seems that the built in functionality in Windows 10 looks for the closest nodes within a radius and if a node is found it will fire a mouse based event.

Multiple Events of the Same Type

If two events of the same type are on an element, stopping the event from bubbling up could prevent one of the events from firing. There are a couple of different ways to handle this using some sort of cache. My initial thoughts were to modify the event object, but we get a reference so I'm thinking a cache solution will have to suffice.

Usually this works as well:

$('#buttonId').on('touchstart click', function(e){
    e.stopPropagation(); e.preventDefault();
    //your code here

});

In my case this worked perfectly:

jQuery(document).on('mouseup keydown touchend', function (event) {
var eventType = event.type;
if (eventType == 'touchend') {
    jQuery(this).off('mouseup');
}
});

The main problem was when instead mouseup I tried with click, on touch devices triggered click and touchend at the same time, if i use the click off, some functionality didn't worked at all on mobile devices. The problem with click is that is a global event that fire the rest of the event including touchend.

Here's a simple way to do it:

// A very simple fast click implementation
$thing.on('click touchstart', function(e) {
  if (!$(document).data('trigger')) $(document).data('trigger', e.type);
  if (e.type===$(document).data('trigger')) {
    // Do your stuff here
  }
});

You basically save the first event type that is triggered to the 'trigger' property in jQuery's data object that is attached to the root document, and only execute when the event type is equal to the value in 'trigger'. On touch devices, the event chain would likely be 'touchstart' followed by 'click'; however, the 'click' handler won't be executed because "click" doesn't match the initial event type saved in 'trigger' ("touchstart").

The assumption, and I do believe it's a safe one, is that your smartphone won't spontaneously change from a touch device to a mouse device or else the tap won't ever register because the 'trigger' event type is only saved once per page load and "click" would never match "touchstart".

Here's a codepen you can play around with (try tapping on the button on a touch device -- there should be no click delay): http://codepen.io/thdoan/pen/xVVrOZ

I also implemented this as a simple jQuery plugin that also supports jQuery's descendants filtering by passing a selector string:

// A very simple fast click plugin
// Syntax: .fastClick([selector,] handler)
$.fn.fastClick = function(arg1, arg2) {
  var selector, handler;
  switch (typeof arg1) {
    case 'function':
      selector = null;
      handler = arg1;
      break;
    case 'string':
      selector = arg1;
      if (typeof arg2==='function') handler = arg2;
      else return;
      break;
    default:
      return;
  }
  this.on('click touchstart', selector, function(e) {
    if (!$(document).data('trigger')) $(document).data('trigger', e.type);
    if (e.type===$(document).data('trigger')) handler.apply(this, arguments);
  });
};

Codepen: http://codepen.io/thdoan/pen/GZrBdo/

Being for me the best answer the one given by Mottie, I'm just trying to do his code more reusable, so this is my contribution:

bindBtn ("#loginbutton",loginAction);

function bindBtn(element,action){

var flag = false;
$(element).bind('touchstart click', function(e) {
    e.preventDefault();
    if (!flag) {
        flag = true;
        setTimeout(function() {
            flag = false;
        }, 100);
        // do something
        action();
    }
    return false;
});

Why not use the jQuery Event API?

http://learn.jquery.com/events/event-extensions/

I've used this simple event with success. It's clean, namespaceable and flexible enough to improve upon.

var isMobile = /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent);
var eventType = isMobile ? "touchstart" : "click";

jQuery.event.special.touchclick = {
  bindType: eventType,
  delegateType: eventType
};

It may be effective to assign to the events 'touchstart mousedown' or 'touchend mouseup' to avoid undesired side-effects of using click.

If you are using jQuery the following worked pretty well for me:

var callback; // Initialize this to the function which needs to be called

$(target).on("click touchstart", selector, (function (func){
    var timer = 0;
    return function(e){
        if ($.now() - timer < 500) return false;
        timer = $.now();
        func(e);
    }
})(callback));

Other solutions are also good but I was binding multiple events in a loop and needed the self calling function to create an appropriate closure. Also, I did not want to disable the binding since I wanted it to be invoke-able on next click/touchstart.

Might help someone in similar situation!

check fast buttons and chost clicks from google https://developers.google.com/mobile/articles/fast_buttons

There are many things to consider when trying to solve this issue. Most solutions either break scrolling or don't handle ghost click events properly.

For a full solution see https://developers.google.com/mobile/articles/fast_buttons

NB: You cannot handle ghost click events on a per-element basis. A delayed click is fired by screen location, so if your touch events modify the page in some way, the click event will be sent to the new version of the page.

I gave an answer there and I demonstrate with a jsfiddle. You can check for different devices and report it.

Basically I use a kind of event lock with some functions that serve it:

/*
 * Event lock functions
 * ====================
 */
function getEventLock(evt, key){
   if(typeof(eventLock[key]) == 'undefined'){
      eventLock[key] = {};
      eventLock[key].primary = evt.type;
      return true;
   }
   if(evt.type == eventLock[key].primary)
      return true;
   else
      return false;
}

function primaryEventLock(evt, key){
   eventLock[key].primary = evt.type;
}

Then, in my event handlers I start by a request to my lock:

/*
 * Event handlers
 * ==============
 */
$("#add").on("touchstart mousedown", addStart);
$("#add").on("touchend mouseup", addEnd);
function addStart(evt){
   // race condition between 'mousedown' and 'touchstart'
   if(!getEventLock(evt, 'add'))
      return;

   // some logic
   now = new Date().getTime();
   press = -defaults.pressDelay;
   task();

   // enable event lock and(?) event repetition
   pids.add = setTimeout(closure, defaults.pressDelay);

   function closure(){
        // some logic(?): comment out to disable repetition
      task();

      // set primary input device
      primaryEventLock(evt, 'add');

      // enable event repetition
      pids.add = setTimeout(closure, defaults.pressDelay);
   }
}
function addEnd(evt){
      clearTimeout(pids.add);
}

I have to stress that the problem is not to respond simply at a event but to NOT respond on both.

Finally, at jsfiddle there is a link to an updated version where I introduce minimal impact at existing code by adding just a simple call to my event lock library both at event start & end handlers along with 2 scope variables eventLock and eventLockDelay.

Instead of the timeout you could use a counter:

var count = 0;
$thing.bind('touchstart click', function(){
  count++;
  if (count %2 == 0) { //count 2% gives the remaining counts when devided by 2
    // do something
  }

  return false
});

Generally you don't want to mix the default touch and non-touch (click) api. Once you move into the world of touch it easier to deal only with the touch related functions. Below is some pseudo code that would do what you want it to.

If you connect in the touchmove event and track the locations you can add more items in the doTouchLogic function to detect gestures and whatnot.

var touchStartTime;
var touchStartLocation;
var touchEndTime;
var touchEndLocation;

$thing.bind('touchstart'), function() {
     var d = new Date();
     touchStartTime = d.getTime();
     touchStartLocation = mouse.location(x,y);
});

$thing.bind('touchend'), function() {
     var d = new Date();
     touchEndTime= d.getTime();
     touchEndLocation= mouse.location(x,y);
     doTouchLogic();
});

function doTouchLogic() {
     var distance = touchEndLocation - touchStartLocation;
     var duration = touchEndTime - touchStartTime;

     if (duration <= 100ms && distance <= 10px) {
          // Person tapped their finger (do click/tap stuff here)
     }
     if (duration > 100ms && distance <= 10px) {
          // Person pressed their finger (not a quick tap)
     }
     if (duration <= 100ms && distance > 10px) {
          // Person flicked their finger
     }
     if (duration > 100ms && distance > 10px) {
          // Person dragged their finger
     }
}

I am trying this and so far it works (but I am only on Android/Phonegap so caveat emptor)

  function filterEvent( ob, ev ) {
      if (ev.type == "touchstart") {
          ob.off('click').on('click', function(e){ e.preventDefault(); });
      }
  }
  $('#keypad').on('touchstart click', '.number, .dot', function(event) {
      filterEvent( $('#keypad'), event );
      console.log( event.type );  // debugging only
           ... finish handling touch events...
  }

I don't like the fact that I am re-binding handlers on every touch, but all things considered touches don't happen very often (in computer time!)

I have a TON of handlers like the one for '#keypad' so having a simple function that lets me deal with the problem without too much code is why I went this way.

Just adding return false; at the end of the on("click touchstart") event function can solve this problem.

$(this).on("click touchstart", function() {
  // Do things
  return false;
});

From the jQuery documentation on .on()

Returning false from an event handler will automatically call event.stopPropagation() and event.preventDefault(). A false value can also be passed for the handler as a shorthand for function(){ return false; }.

I just came up with the idea to memorize if ontouchstart was ever triggered. In this case we are on a device which supports it and want to ignore the onclick event. Since ontouchstart should always be triggered before onclick, I'm using this:

<script> touchAvailable = false; </script>_x000D_
<button ontouchstart="touchAvailable=true; myFunction();" onclick="if(!touchAvailable) myFunction();">Button</button>

Just for documentation purposes, here's what I've done for the fastest/most responsive click on desktop/tap on mobile solution that I could think of:

I replaced jQuery's on function with a modified one that, whenever the browser supports touch events, replaced all my click events with touchstart.

$.fn.extend({ _on: (function(){ return $.fn.on; })() });
$.fn.extend({
    on: (function(){
        var isTouchSupported = 'ontouchstart' in window || window.DocumentTouch && document instanceof DocumentTouch;
        return function( types, selector, data, fn, one ) {
            if (typeof types == 'string' && isTouchSupported && !(types.match(/touch/gi))) types = types.replace(/click/gi, 'touchstart');
            return this._on( types, selector, data, fn);
        };
    }()),
});

Usage than would be the exact same as before, like:

$('#my-button').on('click', function(){ /* ... */ });

But it would use touchstart when available, click when not. No delays of any kind needed :D

The best method I have found is to write the touch event and have that event call the normal click event programatically. This way you have all your normal click events and then you need to add just one event handler for all touch events. For every node you want to make touchable, just add the "touchable" class to it to invoke the touch handler. With Jquery it works like so with some logic to make sure its a real touch event and not a false positive.

$("body").on("touchstart", ".touchable", function() { //make touchable  items fire like a click event
var d1 = new Date();
var n1 = d1.getTime();
setTimeout(function() {
    $(".touchable").on("touchend", function(event) {
        var d2 = new Date();
        var n2 = d2.getTime();
        if (n2 - n1 <= 300) {
            $(event.target).trigger("click"); //dont do the action here just call real click handler
        }
    });
}, 50)}).on("click", "#myelement", function() {
//all the behavior i originally wanted
});

EDIT: My former answer (based on answers in this thread) was not the way to go for me. I wanted a sub-menu to expand on mouse enter or touch click and to collapse on mouse leave or another touch click. Since mouse events normally are being fired after touch events, it was kind of tricky to write event listeners that support both touchscreen and mouse input at the same time.

jQuery plugin: Touch Or Mouse

I ended up writing a jQuery plugin called "Touch Or Mouse" (897 bytes minified) that can detect whether an event was invoked by a touchscreen or mouse (without testing for touch support!). This enables the support of both touchscreen and mouse at the same time and completely separate their events.

This way the OP can use touchstart or touchend for quickly responding to touch clicks and click for clicks invoked only by a mouse.

Demonstration

First one has to make ie. the body element track touch events:

$(document.body).touchOrMouse('init');

Mouse events our bound to elements in the default way and by calling $body.touchOrMouse('get', e) we can find out whether the event was invoked by a touchscreen or mouse.

$('.link').click(function(e) {
  var touchOrMouse = $(document.body).touchOrMouse('get', e);

  if (touchOrMouse === 'touch') {
    // Handle touch click.
  }
  else if (touchOrMouse === 'mouse') {
    // Handle mouse click.
  }
}

See the plugin at work at http://jsfiddle.net/lmeurs/uo4069nh.

Explanation

1. This plugin needs to be called on ie. the body element to track touchstart and touchend events, this way the touchend event does not have to be fired on the trigger element (ie. a link or button). Between these two touch events this plugin considers any mouse event to be invoked by touch.
2. Mouse events are fired only after touchend, when a mouse event is being fired within the ghostEventDelay (option, 1000ms by default) after touchend, this plugin considers the mouse event to be invoked by touch.
3. When clicking on an element using a touchscreen, the element gains the :active state. The mouseleave event is only fired after the element loses this state by ie. clicking on another element. Since this could be seconds (or minutes!) after the mouseenter event has been fired, this plugin keeps track of an element's last mouseenter event: if the last mouseenter event was invoked by touch, the following mouseleave event is also considered to be invoked by touch.