John Davidson

Message:

I'm trying to detect mobile with the user agent string. According MDN there is always the pattern "mobile" on mobiles user agent strings and not on PC, tablet or whatever; but with one exception the iPad's user agent string :(

Basicly I need this for (in)activate a JS function :

examples of user agent strings:

$str = 'Mozilla/5.0 (Linux; Android 10; Redmi Note 9S) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Mobile Safari/537.36';

$str = 'Mozilla/5.0 (iPad; CPU OS 15_5 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/95.0.4638.50 Mobile/15E148 Safari/604.1';

$str = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:101.0) Gecko/20100101 Firefox/101.0';



basic working code in php:

if(preg_match('#Mobile#i', $str)){  

   if(preg_match('#iPad#i', $str)){    $mobile = false; // (ipad)  

   }   else    {   $mobile = true; //(mobile);

       }

} else  {   $mobile = false;    } //others

But:

1. this is inelegant :D


2. I want to improve my knowledge in Regexp, which at the moment I'm using in a simple way without the lookaround or conditionnal stuff.

So since yesterday I try to learn about lookaround and conditionnal, read a lot of tutorials, try a bunch of patterns but I still not find a solution or really understand the lookahead ou lookbehind patterns, neither forcing the match attempt to Fail with (*PRUNE)(*F)

$reg = '/(?(?<=iPad)|Mobile)/i';

$reg = '/(?(?<=Mobile)|(iPad))/i';

$reg='^(?(?=.*Mobile)(?:iPad|)).*$';

$reg='(?(?=Mobile)(?(?=iPad)(*F)|Mobile)|(*F))';

$reg='(?(?=Mobile)(?(?!iPad)(Mobile)|(*F))|(*F))'; //and variations lookbehind /lookahead (positive or negative) 

As there is not conditional patterns within the JS regex engine , all I need is a boolean: false for "mobile" without the ipad, or true for the rest.
Why $reg='(?(?=Mobile)(?(?=iPad)(*F)|Mobile)|(*F))'; return 'mobile' and not fail ?
Is there an elegant solution ? Please help me ... I'm going nuts :D

Cheers.

---

My Answer:
"Mobile" in the user agent string if the device is a mobile device. You can use a regular expression with a conditional statement or negation to detect if the user agent string contains the word "Mobile".

Here is an example using a conditional statement in PHP:

php
$userAgent = $_SERVER['HTTP_USER_AGENT'];

if (preg_match('/Mobile/i', $userAgent)) {
echo 'Mobile device detected';
} else {
echo 'Not a mobile device';
}


This code snippet checks if the user agent string contains the word "Mobile" (case-insensitive) and prints a message accordingly.

Alternatively, you can use negation to check if the user agent string does not contain the word "Mobile":

php
$userAgent = $_SERVER['HTTP_USER_AGENT'];

if (!preg_match('/Mobile/i', $userAgent)) {
echo 'Not a mobile device';
} else {
echo 'Mobile device detected';
}


This code snippet checks if the user agent string does not contain the word "Mobile" and prints a message accordingly.

You can adjust the regular expression pattern and the conditional statement as needed to suit your specific requirements for detecting mobile devices based on the user agent string.