Timothy Huang

Posted on Jun 30, 2020

A simple way to detect if browser is on a mobile device with Javascript

#javascript #mobile #browser

Sometimes we need a little Javascript code snippet to detect if user use mobile device, the simplest way is detecting its browser user agent.

We use the regular expression test to detect if browser is a mobile device like:

if(/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)){
  // true for mobile device
  document.write("mobile device");
}else{
  // false for not mobile device
  document.write("not mobile device");
}

demo is on codepen:

https://codepen.io/timhuang/pen/MWKEZMJ

Reference:

https://stackoverflow.com/questions/3514784/what-is-the-best-way-to-detect-a-mobile-device

Top comments (35)

Oskar Bechtold • Nov 27 '20

Hey,
this is very very unreliable. UserAgent can be changed and as far as I know, iPads want to be treated as desktops now and thus send the same UA in Safari as the Desktop Safari.
Mozilla is of a similar opinion:
developer.mozilla.org/en-US/docs/W...
Hope that helps :-)

Kristy Whalen • Jan 2 '21

I didn't read your link, if you provided a solution using that link, my apologies. Otherwise, do you have a better solution? I'm thinking you do ;-)

Oskar Bechtold • Jan 4 '21

That link shows that using UserAgent is unreliable. If you trust my comment you don't need to read the source :-)

In one of our projects, we have a workaround that checks for screen size, pixel density, touch and other features only available on mobile devices. It seems to work reliably, but it is an Angular module, that I can't share at the moment. Unfortunately, we don't have a plain JS solution yet. That's also the reason why I did search for a simpler way again (for a non-angular project) and found your solution. At first, I was amazed, but then I realized that we have tried this approach in the past and it was not reliable enough for what we needed. So I just wanted to leave this comment here, so people know about it. For this project, I'm back to simple breakpoints considering the width of the screen.

Karl Snyder • Feb 26 '21 • Edited

"Browser identification based on detecting the user agent string is unreliable and is not recommended, as the user agent string is user configurable."

If we require that users don't modify their UserAgent in order to use our website then the UserAgent is perfectly reliable!

Jean Carlo 13 • Apr 7 '21

I agree with @bechtold , using the user agent is a bad idea, there are multiple features to consider, I recommend this article on how to use media queries in JavaScript, I think it is a bester practice.

Karl Snyder • Apr 7 '21

"using the user agent is a bad idea, there are multiple features to consider"

Would you elaborate on why using the user agent is a bad idea? (Also, I'm not sure if you meant features or some other word.)

Gabriel Linassi • Jun 8 '22

@jeancarlo13 the problem with using media queries in JS is that it causes layout shift (FOUC) and it's a problem mainly on above-the-fold UI. Otherwise it's a good approach.

Burak Bilen • Nov 4 • Edited

`export function useMediaQuery(query) {
const subscribe = React.useCallback(
(callback) => {
const matchMedia = window.matchMedia(query);

  matchMedia.addEventListener("change", callback);

  return () => {
    matchMedia.removeEventListener("change", callback);
  };
},
[query]

);

const getSnapshot = () => {
return window.matchMedia(query).matches;
};

const getServerSnapshot = () => {
throw Error("useMediaQuery is a client-only hook");
};

return React.useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
}`

linehammer • Sep 21 '21

You can use JavaScript window.matchMedia() method to detect a mobile device based on the CSS media query.

if (window.matchMedia("(max-width: 767px)").matches)
{
// The viewport is less than 768 pixels wide
document.write("This is a mobile device.");
}

You may also use navigator.userAgentData.mobile .

const isMobile = navigator.userAgentData.mobile;

Another approach would be a responsive media query. You could presume that a mobile phone has a screen size greater than x and less than y. For example:

@media only screen and (min-width: 320px) and (max-width: 600px) {}

net-informations.com/js/iq/default...

Timothy Huang • Jul 11 '22

Thanks for sharing!

Martin Kouba • Sep 6 '23

Unfortunately navigator.userAgentData.mobile appears to be not widely supported yet

caniuse.com/?search=userAgentData
caniuse.com/?search=mobile

DrGaud • Nov 12 '20

Thank you for this,
I have ended up placing it in a view class as a getter function

get isMobile(){
        // credit to Timothy Huang for this regex test: 
        // https://dev.to/timhuang/a-simple-way-to-detect-if-browser-is-on-a-mobile-device-with-javascript-44j3
        if(/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)){
            return true
       }
       else{
            return false
       }
    }

Honestly thanks for this eloquent regex test.

Timothy Huang • May 20 '21

thanks for your improvement! :)

Oskar Codes • Jun 4 '21

Make it shorter like this:

function isMobile() {
  return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
}

Timothy Huang • Jun 5 '21

Thank you!

Dima • Jul 5 '22 • Edited

const isMobile = () => /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);

Timothy Huang • Jul 5 '22

Wow, really short! Thanks for your improvement.

andreseduardop • May 21 '21

It worked very well for me. Thanks, @timhuang
I adapted the modification proposed by @drgaud

function isMobile () {
   // credit to Timothy Huang for this regex test:
   // https://dev.to/timhuang/a-simple-way-to-detect-if-browser-is-on-a-mobile-device-with-javascript-44j3
   if (/ Android | webOS | iPhone | iPad | iPod | BlackBerry | IEMobile | Opera Mini / i.test (navigator.userAgent)) {
       return true
   }
   else {
       return false
   };
};

MK1331 • Nov 24 '21 • Edited

Alternatively, you can use

navigator.mediaDevices.enumerateDevices().then(md => { console.log(md) }); and use field

MediaDeviceInfo.kind Read only
Returns an enumerated value that is either "videoinput", "audioinput" or "audiooutput".

and

MediaDeviceInfo.groupId Read only
Returns a DOMString that is a group identifier. Two devices have the same group identifier if they belong to the same physical device — for example a monitor with both a built-in camera and a microphone.

That is, if several "videoinput" and their groupId are the same, most likely this is a mobile device, since there are more than one laptop and monitor with two cameras and more.

That function suported all desktop and mobile browsers except IE.

Timothy Huang • Feb 10 '22

Great! An alternative solution. Thanks!

T. Greg O'Neil • Aug 10 '22

'ontouchstart' in window
=> true for mobile devices
=> false for desktop environment

Daniel Vivar • Oct 10 '22

Some desktops have touchscreen devices, this is not reliable

T. Greg O'Neil • Oct 11 '22

I think you've taken the question too literally. The main issue behind the question is for developers to distinguish whether their JavaScript code needs to handle touch events vs click events, and not to figure out if someone can literally lug their device around in a mobile manner. Determining if touch events are in the window object is a simple way to determine this. Cheers!

Some Dev • Aug 31 '23 • Edited

I think you've taken the question too literally. The main issue behind the question is for developers to distinguish whether their JavaScript code needs to handle touch events vs click events

No, this is very often not true.

In my case, I'm interested in this right now because I need to default the UI rendering of a webpage to relate better to our mobile app when the user is on mobile.

If the user lands on a marketing page, for example, we want to frontload the marketing copy that talks about the mobile features of our product suite. That's not relevant to someone running Windows on a touchscreen laptop.

linehammer • Oct 25 '21

User Agent detection is not a recommended technique for modern web apps. There is a JavaScript API built-in for detecting media. The JavaScript window.matchMedia() method returns a MediaQueryList object representing the results of the specified CSS media query string. You can use this method to detect a mobile device based on the CSS media query.

$(document).ready(function(){
let isMobileDevice = window.matchMedia("only screen and (max-width: 760px)").matches;
if(isMobileDevice){
// The viewport is less than 768 pixels wide
//Conditional script here
} else{
//The viewport is greater than 700 pixels wide
alert("This is not a mobile device.");
}
});

You can use above script to do show/hide elements depending on the screen size.

net-informations.com/js/progs/mobi...

Mehedi Islam Ripon • Jan 19 '22

This is working fine! Thank you.

Timothy Huang • Feb 10 '22

Great! I hope this could help who need to detect if browser on a mobile device.
Thanks for your visiting.

KAK KOTYAVO! • May 12 '21

an interesting solution for new browsers, and most importantly fast:
stackoverflow.com/questions/783868...?

a pity that display media-queries are not available for very ancient devices and browsers (hello Safari)

for server side detect device in production, i use packet npmjs.com/package/node-device-dete... (I'm the author, maybe I'm PR late)

Timothy Huang • Feb 10 '22

Thank you!

KAK KOTYAVO! • Jul 11 '22

I have made some improvements to the speed of detecting devices and clients, if you also use the library, I recommend updating the dependency to the latest version.