What's the best way to detect a 'touch screen' device using JavaScript?

Question

I\'ve written a jQuery plug-in that\'s for use on both desktop and mobile devices. I wondered if there is a way with JavaScript to detect if the device has touch screen capa

Answer 1

The biggest "gotcha" with trying to detect touch is on hybrid devices that support both touch and the trackpad/mouse. Even if you're able to correctly detect whether the user's device supports touch, what you really need to do is detect what input device the user is currently using. There's a detailed write up of this challenge and a possible solution here.

Basically the approach to figuring out whether a user just touched the screen or used a mouse/ trackpad instead is to register both a touchstart and mouseover event on the page:

document.addEventListener('touchstart', functionref, false) // on user tap, "touchstart" fires first
document.addEventListener('mouseover', functionref, false) // followed by mouse event, ie: "mouseover"

A touch action will trigger both of these events, though the former (touchstart) always first on most devices. So counting on this predictable sequence of events, you can create a mechanism that dynamically adds or removes a can-touch class to the document root to reflect the current input type of the user at this moment on the document:

;(function(){
    var isTouch = false //var to indicate current input type (is touch versus no touch) 
    var isTouchTimer 
    var curRootClass = '' //var indicating current document root class ("can-touch" or "")
     
    function addtouchclass(e){
        clearTimeout(isTouchTimer)
        isTouch = true
        if (curRootClass != 'can-touch'){ //add "can-touch' class if it's not already present
            curRootClass = 'can-touch'
            document.documentElement.classList.add(curRootClass)
        }
        isTouchTimer = setTimeout(function(){isTouch = false}, 500) //maintain "istouch" state for 500ms so removetouchclass doesn't get fired immediately following a touch event
    }
     
    function removetouchclass(e){
        if (!isTouch && curRootClass == 'can-touch'){ //remove 'can-touch' class if not triggered by a touch event and class is present
            isTouch = false
            curRootClass = ''
            document.documentElement.classList.remove('can-touch')
        }
    }
     
    document.addEventListener('touchstart', addtouchclass, false) //this event only gets called when input type is touch
    document.addEventListener('mouseover', removetouchclass, false) //this event gets called when input type is everything from touch to mouse/ trackpad
})();

More details here.

Answer 2

Actually, I researched this question and consider all situations. because it is a big issue on my project too. So I reach the below function, it works for all versions of all browsers on all devices:

const isTouchDevice = () => {
  const prefixes = ['', '-webkit-', '-moz-', '-o-', '-ms-', ''];
  const mq = query => window.matchMedia(query).matches;

  if (
    'ontouchstart' in window ||
    (window.DocumentTouch && document instanceof DocumentTouch)
  ) {
    return true;
  }
  return mq(['(', prefixes.join('touch-enabled),('), 'heartz', ')'].join(''));
};

Hint: Definitely, the isTouchDevice just returns boolean values.

Answer 3

jQuery v1.11.3

There is a lot of good information in the answers provided. But, recently I spent a lot of time trying to actually tie everything together into a working solution for the accomplishing two things:

1. Detect that the device in use is a touch screen type device.
2. Detect that the device was tapped.

Besides this post and Detecting touch screen devices with Javascript, I found this post by Patrick Lauke extremely helpful: https://hacks.mozilla.org/2013/04/detecting-touch-its-the-why-not-the-how/

Here is the code...

$(document).ready(function() {
//The page is "ready" and the document can be manipulated.

    if (('ontouchstart' in window) || (navigator.maxTouchPoints > 0) || (navigator.msMaxTouchPoints > 0))
    {
      //If the device is a touch capable device, then...
      $(document).on("touchstart", "a", function() {

        //Do something on tap.

      });
    }
    else
    {
      null;
    }
});

Important! The *.on( events [, selector ] [, data ], handler ) method needs to have a selector, usually an element, that can handle the "touchstart" event, or any other like event associated with touches. In this case, it is the hyperlink element "a".

Now, you don't need to handle the regular mouse clicking in JavaScript, because you can use CSS to handle these events using selectors for the hyperlink "a" element like so:

/* unvisited link */
a:link 
{

}

/* visited link */
a:visited 
{

}

/* mouse over link */
a:hover 
{

}

/* selected link */
a:active 
{

}

Note: There are other selectors as well...

Answer 4

If you use Modernizr, it is very easy to use Modernizr.touch as mentioned earlier.

However, I prefer using a combination of Modernizr.touch and user agent testing, just to be safe.

var deviceAgent = navigator.userAgent.toLowerCase();

var isTouchDevice = Modernizr.touch || 
(deviceAgent.match(/(iphone|ipod|ipad)/) ||
deviceAgent.match(/(android)/)  || 
deviceAgent.match(/(iemobile)/) || 
deviceAgent.match(/iphone/i) || 
deviceAgent.match(/ipad/i) || 
deviceAgent.match(/ipod/i) || 
deviceAgent.match(/blackberry/i) || 
deviceAgent.match(/bada/i));

if (isTouchDevice) {
        //Do something touchy
    } else {
        //Can't touch this
    }

If you don't use Modernizr, you can simply replace the Modernizr.touch function above with ('ontouchstart' in document.documentElement)

Also note that testing the user agent iemobile will give you broader range of detected Microsoft mobile devices than Windows Phone.

Also see this SO question

Answer 5

Since the introduction of interaction media features you simply can do:

if(window.matchMedia("(pointer: coarse)").matches) {
    // touchscreen
}

https://www.w3.org/TR/mediaqueries-4/#descdef-media-any-pointer

Update (due to comments): The above solution is to detect if a "coarse pointer" - usually a touch screen - is the primary input device. In case you want to dectect if a device with e.g. a mouse also has a touch screen you may use any-pointer: coarse instead.

For more information have a look here: Detecting that the browser has no mouse and is touch-only

Answer 6

Many of these work but either require jQuery, or javascript linters complain about the syntax. Considering your initial question asks for a "JavaScript" (not jQuery, not Modernizr) way of solving this, here's a simple function that works every time. It's also about as minimal as you can get.

function isTouchDevice() {
    return !!window.ontouchstart;
}

console.log(isTouchDevice());

One last benefit I'll mention is that this code is framework and device agnostic. Enjoy!