What is the best way to detect a mobile device?

Question

Editor's note: user agent detection is not a recommended technique for modern web apps. See the comments below this answer for confirmation of this fact. It is suggested to use one of the other answers using feature detection and/or media queries.

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Instead of using jQuery you can use simple JavaScript to detect it:

if( /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent) ) {
 // some code..
}

Or you can combine them both to make it more accessible through jQuery...

$.browser.device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));

Now $.browser will return "device" for all above devices

Note: $.browser removed on jQuery v1.9.1. But you can use this by using jQuery migration plugin Code

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A more thorough version:

var isMobile = false; //initiate as false
// device detection
if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|ipad|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(navigator.userAgent) 
    || /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(navigator.userAgent.substr(0,4))) { 
    isMobile = true;
}

For me small is beautiful so I'm using this technique:

In CSS file:

/* Smartphones ----------- */
@media only screen and (max-width: 760px) {
  #some-element { display: none; }
}

In jQuery/JavaScript file:

$( document ).ready(function() {      
    var is_mobile = false;

    if( $('#some-element').css('display')=='none') {
        is_mobile = true;       
    }

    // now I can use is_mobile to run javascript conditionally

    if (is_mobile == true) {
        //Conditional script here
    }
 });

My objective was to have my site "mobile-friendly". So I use CSS Media Queries do show/hide elements depending on the screen size.

For example, in my mobile version I don't want to activate the Facebook Like Box, because it loads all those profile images and stuff. And that's not good for mobile visitors. So, besides hiding the container element, I also do this inside the jQuery code block (above):

if(!is_mobile) {
    (function(d, s, id) {
        var js, fjs = d.getElementsByTagName(s)[0];
        if (d.getElementById(id)) return;
        js = d.createElement(s); js.id = id;
        js.src = "//connect.facebook.net/pt_PT/all.js#xfbml=1&appId=210731252294735";
        fjs.parentNode.insertBefore(js, fjs);
    }(document, 'script', 'facebook-jssdk'));
}

You can see it in action at http://lisboaautentica.com

I'm still working on the the mobile version, so it's still not looking as it should, as of writing this.

Update by dekin88

There is a JavaScript API built-in for detecting media. Rather than using the above solution simply use the following:

$(function() {      
    let isMobile = window.matchMedia("only screen and (max-width: 760px)").matches;

    if (isMobile) {
        //Conditional script here
    }
 });

Browser Supports: http://caniuse.com/#feat=matchmedia

The advantage of this method is that it's not only simpler and shorter, but you can conditionally target different devices such as smartphones and tablets separately if necessary without having to add any dummy elements into the DOM.

According to Mozilla - Browser detection using the user agent:

In summary, we recommend looking for the string “Mobi” anywhere in the User Agent to detect a mobile device.

Like this:

if (/Mobi/.test(navigator.userAgent)) {
    // mobile!
}

This will match all common mobile browser user agents, including mobile Mozilla, Safari, IE, Opera, Chrome, etc.

Update for Android

EricL recommends testing for Android as a user agent also, as the Chrome user agent string for tablets does not include "Mobi" (the phone versions do however):

if (/Mobi|Android/i.test(navigator.userAgent)) {
    // mobile!
}

A simple and effective one-liner:

function isMobile() { return ('ontouchstart' in document.documentElement); }

However above code doesn't take into account the case for laptops with touchscreen. Thus, I provide this second version, based on @Julian solution:

function isMobile() {
  try{ document.createEvent("TouchEvent"); return true; }
  catch(e){ return false; }
}

It's not jQuery, but I found this: http://detectmobilebrowser.com/

It provides scripts to detect mobile browsers in several languages, one of which is JavaScript. That may help you with what you're looking for.

However, since you are using jQuery, you might want to be aware of the jQuery.support collection. It's a collection of properties for detecting the capabilities of the current browser. Documentation is here: http://api.jquery.com/jQuery.support/

Since I don't know what exactly what you're trying to accomplish, I don't know which of these will be the most useful.

All that being said, I think your best bet is to either redirect or write a different script to the output using a server-side language (if that is an option). Since you don't really know the capabilities of a mobile browser x, doing the detection, and alteration logic on the server side would be the most reliable method. Of course, all of that is a moot point if you can't use a server side language :)

Sometimes it is desired to know which brand device a client is using in order to show content specific to that device, like a link to the iPhone store or the Android market. Modernizer is great, but only shows you browser capabilities, like HTML5, or Flash.

Here is my UserAgent solution in jQuery to display a different class for each device type:

/*** sniff the UA of the client and show hidden div's for that device ***/
var customizeForDevice = function(){
    var ua = navigator.userAgent;
    var checker = {
      iphone: ua.match(/(iPhone|iPod|iPad)/),
      blackberry: ua.match(/BlackBerry/),
      android: ua.match(/Android/)
    };
    if (checker.android){
        $('.android-only').show();
    }
    else if (checker.iphone){
        $('.idevice-only').show();
    }
    else if (checker.blackberry){
        $('.berry-only').show();
    }
    else {
        $('.unknown-device').show();
    }
}

This solution is from Graphics Maniacs http://graphicmaniacs.com/note/detecting-iphone-ipod-ipad-android-and-blackberry-browser-with-javascript-and-php/

Found a solution in: http://www.abeautifulsite.net/blog/2011/11/detecting-mobile-devices-with-javascript/.

var isMobile = {
    Android: function() {
        return navigator.userAgent.match(/Android/i);
    },
    BlackBerry: function() {
        return navigator.userAgent.match(/BlackBerry/i);
    },
    iOS: function() {
        return navigator.userAgent.match(/iPhone|iPad|iPod/i);
    },
    Opera: function() {
        return navigator.userAgent.match(/Opera Mini/i);
    },
    Windows: function() {
        return navigator.userAgent.match(/IEMobile/i);
    },
    any: function() {
        return (isMobile.Android() || isMobile.BlackBerry() || isMobile.iOS() || isMobile.Opera() || isMobile.Windows());
    }
};

And then to verify if its a Mobile, you can test using:

if(isMobile.any()) {
   //some code...
}